Northern Territory Midwives' Collection Trends in the health of mothers and babies Northern Territory 1986–95 Peter G Markey Edouard T d’Espaignet John R Condon Maxene Woods Epidemiology Branch Territory Health Services Darwin This work is copyright. It may be reproduced in whole or in part for study or training purposes subject to the inclusion of an acknowledgement of the source and no commercial usage or sale. Reproduction for purposes other than those indicated above requires the written permission of the Secretary of Territory Health Services. The suggested citation is: Markey PG, d'Espaignet ET, Condon JR & Woods M (1998). Trends in the health of mothers and babies, Northern Territory, 1986–95. Territory Health Services, Darwin. Copyright © 1998 by Territory Health Services Printed by the Government Printer of the Northern Territory ISBN 0 7245 3343 5 Printed March 1998 General inquiries Data from the NT Midwives’ Collection can be made available for research and program evaluation. Requests for information must be made in writing and must state the institutional affiliation of the researcher and the purpose for which the data are requested. In all cases, the request must satisfy strict ethical and confidentiality requirements before data can be released. Requests for data, and comments on the publication should be sent to: Northern Territory Midwives' Collection Epidemiology Branch Territory Health Services PO Box 40596 Casuarina NT 0811 Telephone: (08) 8999 2637 Fax: (08) 8999 2618 E-Mail: epidemiology@nt.gov.au ii Contents Contents ............................................................................................................................................. iii Introduction ........................................................................................................................................ v Acknowledgements............................................................................................................................ vii Map of health districts in the Northern Territory ........................................................................... viii Summary ....................................................................................................................................... 1 Mothers Demography Country of birth ............................................................................................................................. 3 Indigenous Status........................................................................................................................... 4 Fertility .......................................................................................................................................... 5 Parity ............................................................................................................................................. 6 Age of mother ................................................................................................................................ 8 Antenatal Gestation ...................................................................................................................................... 10 Antenatal care in the first trimester of pregnancy ........................................................................ 12 Antenatal care in the first trimester of pregnancy by district ....................................................... 13 Antenatal procedures Ultrasound ................................................................................................................................... 14 Amniocentesis for older mothers.................................................................................................. 15 Antenatal medical conditions Anaemia ....................................................................................................................................... 16 Gestational diabetes ..................................................................................................................... 18 Antenatal obstetric complications Pre-eclampsia .............................................................................................................................. 20 Intra-uterine growth retardation................................................................................................... 21 Labour, delivery and puerperium Induction of labour ...................................................................................................................... 22 Induction of labour by hospital .................................................................................................... 23 Caesarean section ........................................................................................................................ 24 Caesarean section by hospital ...................................................................................................... 25 Instrumental delivery ................................................................................................................... 26 Retained placenta ......................................................................................................................... 27 Post-partum haemorrhagic complications .................................................................................... 28 Health service use Confinements out of hospital ....................................................................................................... 29 Average duration of postnatal hospital stay ................................................................................. 30 Average duration of postnatal stay by hospital ............................................................................ 31 iii Babies Demography Indigenous Status......................................................................................................................... 34 Morbidity Foetal distress .............................................................................................................................. 35 Birthweight .................................................................................................................................. 36 Average birthweight ..................................................................................................................... 38 Average birthweight by district .................................................................................................... 39 Apgar scores less than 7 .............................................................................................................. 40 Neonatal infection ........................................................................................................................ 41 Health service use Hospital of birth........................................................................................................................... 42 Average duration of stay in hospital ............................................................................................43 Mortality Foetal deaths ................................................................................................................................ 44 Neonatal deaths ........................................................................................................................... 45 Perinatal deaths............................................................................................................................ 46 Infant deaths ................................................................................................................................ 47 Appendix ............................................................................................................. 48 iv Introduction The primary purpose of this report is to inform and encourage community discussion on the health of mothers and their babies, the services they require and the adequacy of the services currently available to them. In addition, the report aims to provide feedback to midwives, Aboriginal health workers, community health nurses and medical practitioners involved with maternal and child health. Ultimately, this report aims to act as a source of information for the community, policy makers, health planners and health project implementation teams in the initiation, development, implementation and evaluation of health programs. The Northern Territory’s Midwives' Collection, maintained by the Epidemiology Branch of Territory Health Services, has been operating since 1986. The Collection is a population-based census of all births in public and private hospitals as well as home births that occurred in the Northern Territory. It includes all births of 20 weeks gestation or 400 grams. Notification forms, completed by the midwife attending the delivery of the baby, formed the basis of the Collection and provided demographic information on the mother as well as information on her health, pregnancy, labour and delivery, and the health of the baby. For deliveries which occurred out of hospital, the form was completed by the community midwife or nurse involved in the delivery. For planned homebirths, the Collection relied on the enthusiasm and support of NT Homebirths Association. Although most homebirths were reported for the decade under study, it is likely that some also went unreported. This report presents information on trends in perinatal statistics in the Northern Territory for the ten year period extending from 1986 to 1995. During that time, information from the Collection has been provided in a series of reports published annually. The information in the annual publications was compiled from several additional sources which included the termination of pregnancy notification system, the congenital abnormality notification system, the hospital morbidity database, the NT Register of Births, Deaths and Marriages, and the NT Coroner’s Offices. Although the databases used to produce this report were the same as those used in the production of the annual reports, there are some discrepancies between the results presented here and those from the annual reports. There are several reasons for this. Firstly, the yearly databases are updated whenever new information becomes available and this means that the databases used in the production of this report could differ from those used for the preparation of the annual reports. Secondly, analysis of the data for the period 1986–90 revealed inconsistencies which necessitated further correction. Thirdly, the Darwin Private Hospital which commenced obstetric services in 1987, did not consistently report data until 1990 so the data for the period 1987–89 are incomplete and care should be taken with interpretation for these years. Finally, this report covers all confinements to women who were NT residents and delivered in the NT in the years 1986– 95. Although the annual publications reported on all deliveries that occurred in the Territory, this report has focused only on delivery by NT residents only. Women who usually resided in other States but who delivered in the NT were not included (nor were usual NT residents who delivered elsewhere). Completeness of data for report Data from the NT Midwives' Collection and the Birth Register maintained by the Registrar of Births, Deaths and Marriages are the two major sources of information on the number of births in the Northern Territory. Data from the Birth Register is published by the Australian Bureau of Statistics (ABS). A comparison of these two datasets indicated a slightly higher number in the Birth Register except for the years 1998 and 1989 when there were substantially more births in the Birth Register than in the Midwives' Collection (Table A). The Birth register data (published by ABS) refer to the number of livebirths born in the Northern Territory to mothers usually resident in the NT and in the year in which the birth actually occurred. v Number of livebirths 4000 3000 3500 ABS data 2500 Midwives collection 2000 1500 1000 500 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table A: Difference in the number of livebirths reported by the Australian Bureau of Statistics and the NT Midwives Collection, 1986–95 ABS data Midwives’ collection 1986 3239 3172 1987 3218 3102 1988 1989 1990 1991 Number of livebirths 3320 3331 3383 3511 2819 2730 3271 3409 1992 3605 3508 1993 3523 3416 1994 3466 3403 1995 3553 3501 Births for whom a Midwife form was not received 67 116 501 601 112 102 97 107 63 52 Note: Source of ABS data: ABS Catalogue No. 3301.0, 1992-95 Except for the years 1988 and 1989, the smaller number of births from the Midwives Collection reflects those births for which a Midwives’ Collection form was not completed (table A and graph). The substantial difference in the data for these two years results from the transfer of deliveries from Royal Darwin Hospital to the then newly opened Darwin Private Hospital. The Private Hospital did not start routine reporting of its deliveries to the Midwives Collection until 1990. Contents of report The report is divided into two main sections. The first section deals with the mothers, and includes both their demographic characteristics and the factors that characterised their antenatal experience, including the timing of any antenatal care, the conditions, complications and procedures they underwent, and their delivery experience. The second section is about the babies, and addresses issues concerning the perinatal period, including morbidity following birth and survival during their first year of life. vi Acknowledgements The authors wish to acknowledge and thank the midwives of the Northern Territory who have selflessly provided information to the NT Midwives' Collection on the health status of mothers and their babies since 1986. Thanks are also extended to the medical records staff of all hospitals in the Northern Territory, the senior midwife at Darwin Private Hospital and at Alice Springs Alukura, the Darwin and Alice Springs Home Births Group Inc., and the NT Registrar General for providing additional information on births, as well as perinatal and infant deaths in the Northern Territory. Thanks also to the medical officers who provided information on deaths, and those who assisted with the classification of perinatal and infant deaths. In addition we would like to express our thanks to the Northern Territory Coroners. The authors also express their thanks to Sheree Dening, Fiona Medigovich and Diane Frey for assisting with the formatting of the report. Map of health districts in the Northern Territory viii ....... SummarySummarySummarySummarySummary • This report summarises trends in the health of Northern Territory mothers and babies from 1986 to 1995 as reported to the NT midwives' collection. • There was an increase in the annual number of births in the NT (to NT resident mothers) from 3,206 in 1986 to 3,537 in 1995. • Although Aboriginal women make up about a quarter of the total female population of childbearing age, they consistently contributed about a third of all births in the NT during the period 1986–95. Aboriginal women had a persistently higher total fertility rate compared with non-Aboriginal women, however, there was a steady decline in the total fertility rate of Aboriginal women from 3.1 children per woman in 1986 to 2.6 in 1995. In contrast, there was a small increase in the total fertility rate of non-Aboriginal women from an average of 1.8 children per woman in the late 1980s to 2.0 in 1995. • The proportion of mothers under the age of 20 years was persistently higher among Aboriginal women compared with non-Aboriginal women, but fell in both groups. The proportion of Aboriginal mothers below the age of 20 years fell from 36% in 1986 to 29% in 1995, while that of non-Aboriginal mothers fell from six to four percent. The proportion of non-Aborginal mothers aged 35 years and over increased from 7.3% in 1986 to 12.4% in 1995. The proportion of Aboriginal mothers in that age group did not change. • The proportion of mothers with a documented diagnosis of anaemia increased throughout the decade in both Aboriginal and non-Aboriginal mothers to be 19% and 3% respectively in 1995. This increase may be due to improved surveillance and documentation. • Intra-uterine growth retardation (IUGR) was diagnosed less frequently in both Aboriginal and non- Aboriginal women. The proportion of Aboriginal mothers with IUGR fell from 12% in 1987 to 4% in 1995 and in non-Aboriginal mothers from 5.2% to 1.9%. • The proportion of mothers delivering preterm was consistently higher among Aboriginal mothers than non-Aboriginal mothers. There was little change in the proportion delivering prematurely in either group in the ten-year period from 1986 to 1995. • The rates of caesarean section were persistently higher among Aboriginal mothers. The rates remained steady throughout the late 1980s but increased throughout the 1990s for both Aboriginal and non- Aboriginal mothers. • The proportion of Aboriginal births occurring out of hospital decreased from a high of 11% in 1987 to 4.5% in 1995. The proportion of non-Aboriginal births out of hospital remains low, but some of these may not have been reported. • The proportion of Aboriginal babies classified as low birthweight (less than 2,500 grams) fell throughout the decade from 15% in 1986 to 12.6% in 1995. It is still higher than the proportion of non-Aboriginal babies of low birth weight, which has remained steady at around six percent. The average birthweight of Aboriginal babies rose by 85 grams which was 30% of the difference between Aboriginal and non-Aboriginal birthweights in 1986. • There was an improvement in the survival rates of Aboriginal babies (as measured by the stillbirth, perinatal and infant mortality rates), but Aboriginal babies still have substantially higher mortality rates than non-Aboriginal babies. Aboriginal infant mortality rate fell from 36 infant deaths per thousand livebirths in 1986 to 18 deaths per thousand livebirths in 1995. 1 ....... MothersMothersMothersMothersMothers Demography • Country of birth • Indigenous status • Fertility • Parity • Age of mother Antenatal • Gestation • Antenatal care in the first trimester of pregnancy • Antenatal care in the first trimester of pregnancy by district Antenatal procedures • Ultrasound • Amniocentesis for older mothers Antenatal medical conditions • Anaemia • Gestational diabetes in mothers aged 20-29 years • Gestational diabetes in mothers aged 30 years and over Antenatal obstetric complications • Pre-eclampsia • Intra-uterine growth retardation Labour delivery and puerperium • Induction of labour • Induction of labour by hospital • Caesarean section • Caesarean section by hospital • Instrumental delivery • Retained placenta • Post-partum haemorrhagic complications Health service use • Confinements out of hospital • Average duration of stay in hospital after delivery • Average duration of stay in hospital after delivery by hospital 2 ....... MothersMothersMothersMothersMothers.............. Demography Demography Demography Demography Demography Country of birth 0 1 2 3 4 5 6 7 8 9 10 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Europe SE Asia & China NZ & Oceania All other overseas countries Table 1: Country of birth of mother, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Born in Australia 82.7 83.5 83.6 84.7 83.4 83.9 84.0 84.8 85.1 84.5 Born overseas 17.3 16.5 16.4 15.3 16.6 16.1 16.0 15.2 14.9 15.5 South East Asia & China 5.2 5.2 5.1 4.8 5.5 5.0 5.5 5.4 4.9 5.3 United Kingdom & Ireland 4.3 3.7 3.7 3.4 4.3 4.2 3.9 3.3 3.1 3.7 Rest of Europe 3.1 2.5 2.4 2.3 1.7 2.1 1.7 1.4 1.4 1.6 New Zealand & Oceania 3.1 2.7 2.8 2.9 3.0 2.9 3.2 3.0 3.6 3.0 Other overseas countries 1.7 2.5 2.4 1.9 2.2 1.9 1.7 2.2 1.9 1.9 • 85% of the women who gave birth in 1995, were born in Australia compared with 83% in 1986. • The proportion of mothers born overseas varied between 15 and 17 percent, and remained fairly stable. • The proportion of mothers born in Europe (including the United Kingdom and Ireland) has declined from 7.4% of all mothers who gave birth in 1986 to 5.3% in 1995. • There has been no change in the proportion of mothers born in South East Asia and China. 3 ....... MothersMothersMothersMothersMothers.......... DemographyDemographyDemographyDemographyDemography Indigenous Status Number of confinements Non-Aboriginal 1000 1500 2000 Aboriginal 500 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 2: Number and proportion of confinements by Indigenous Status, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Number Aboriginal 1053 1113 1067 1105 1121 1151 1184 1163 1146 1169 Non-Aboriginal 2127 2004 1769 1638 2169 2266 2325 2254 2249 2319 Total 3180 3117 2836 2743 3290 3417 3509 3417 3395 3488 Percent Aboriginal 33.1 35.7 37.6 40.3 34.1 33.7 33.7 34.0 33.8 33.5 Non-Aboriginal 66.9 64.3 62.4 59.7 65.9 66.3 66.3 66.0 66.2 66.5 • There has been a steady increase in the number of confinements to women residing in the Northern Territory. • A total of 3180 women resident in the Northern Territory confined in 1986 compared with 3488 in 1995, reflecting an increase in the number of women of child-bearing age during these years. • Two in every three of these confinements were to non-Aboriginal women. • The apparent decline in the number of non- Aboriginal women who confined in 1988 and 1989 is spurious. Information on births in the Darwin Private Hospital, which opened in late 1987, were not reported to the Midwives' Collection in 1988 and 1989. 4 ....... MothersMothersMothersMothersMothers.......... DemographyDemographyDemographyDemographyDemography Fertility No. of children per woman 2 3 Aboriginal Non-Aboriginal 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 3: Total fertility rate – Number of children per woman, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Aboriginal 3.1 2.8 2.6 2.7 2.6 2.6 2.8 2.7 2.6 2.6 Non-Aboriginal 1.8 1.8 1.8 1.8 1.8 1.9 1.9 1.9 1.9 2.0 • The total fertility rate (TFR) is a useful summary measure of fertility. It is the number of children a woman would have, if throughout her reproductive years, she had children at the age- specific rates that were observed in any one year. This rate is obtained by summing the age- specific fertility rates for one particular year. • As described earlier, data on births had not been reported for the Darwin Private Hospital for the years 1987 to 1989. As over 99% of the births in that hospital are to non-Aboriginal women, the data for Aboriginal women were not affected. For non-Aboriginal women, the fertility rates for 1987–89 were estimated as the average of the ratres for 1986 and 1990 (both of which were 1.8). • After an initial fall from 3.1 children per woman in 1986 to 2.6 in 1988, there has not been much change in the Aboriginal total fertility. • A somewhat different pattern was observed for non-Aboriginal women with a small increase in total fertility rate from 1.8 in the late 1980s to 2.0 in 1995. 5 ....... MothersMothersMothersMothersMothers.......... DemographyDemographyDemographyDemographyDemography Parity Percent 30 35 40 45 Aboriginal Non-Aboriginal 25 20 15 10 5 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 4: Proportion of mothers having their first child, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 percent Aboriginal 31.6 29.8 28.6 31.2 30.2 33.3 33.4 31.6 33.2 31.7 Non-Aboriginal 42.2 43.5 43.7 43.5 43.7 42.5 44.6 42.2 42.9 43.4 Total 38.7 38.6 38 38.5 39.1 39.4 40.9 38.6 39.6 39.5 • Parity refers to the number of previous pregnancies of at least 20 weeks gestation. Women having their first child (i.e. parity zero) are at a higher risk of complication, due to both physiological and psychological inexperience. • This inexperience affects a variety of physiological processes, including the coordination of uterine contractions, the movement of the foetus through the birth canal and the response to pain. • Of the Aboriginal women who had a baby in the period 1986–95, about 30% were having their first child compared with about 43% among the non-Aboriginal women. Hence, 70% of Aboriginal women had a second or higher order birth in contrast to 57% of non-Aboriginal women. • The proportions fluctuated throughout the decade with little overall change within the two groups of mothers. 6 ....... MothersMothersMothersMothersMothers.......... DemographyDemographyDemographyDemographyDemography Parity Percent 20 18 2 Non-Aboriginal 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 4 6 8 10 12 14 16 Aboriginal Table 5: Proportion of mothers having their fourth or higher order child, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 13.4 17.2 15.9 14.4 15.1 13.3 13.4 13.4 12.4 13.1 Non-Aboriginal 3.0 3.0 3.0 3.5 3.2 2.7 2.5 3.2 2.5 2.9 Total 6.4 8.1 7.9 7.9 7.3 6.3 6.2 6.7 5.8 6.3 • Mothers with a parity of three or more are at a greater risk of complications associated with delivery such as malpresentation, precipitate labour, uterine rupture and post-partum haemorrhage. • There is also a higher risk of Rhesus isoimmunisation although this condition is nowadays rare. • The proportion of non-Aboriginal mothers with a high parity did not change over the decade, while the proportion of Aboriginal mothers fell from 1987 after an initial rise. • The proportion of mothers with high parity was over three times higher in Aboriginal mothers than in non-Aboriginal mothers. 7 ....... MothersMothersMothersMothersMothers.......... DemographyDemographyDemographyDemographyDemography Age of mother Percent 50 45 40 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 5 10 15 20 25 30 35 Non-Aboriginal Aboriginal Table 6: Proportion of mothers under 20 years of age, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 36.1 35.5 32.4 32.5 33.1 31.9 31.8 29.0 30.5 29.0 Non-Aboriginal 8.2 6.8 7.5 7.7 7.0 5.2 6.1 6.0 5.8 6.1 Total 17.4 17.1 16.9 17.7 15.9 14.2 14.8 13.8 14.1 13.8 • Maternal age less than twenty is associated with a higher complication rate, both in baby and mother during pregnancy and at delivery of the baby. • This is due to several factors including a relative physiological and psychological immaturity, a high proportion of inexperienced first time mothers, and generally fewer social support structures to assist the mother both antenatally and postnatally. • For these reasons teenage pregnancy is also associated with higher perinatal and infant mortality. • The proportion of teenage Aboriginal mothers was about four times that of non-Aboriginal mothers. However, the proportion decreased from 36% in 1986 to 29% in 1995 for Aboriginal mothers and correspondingly from 8% in 1986 to 6% in 1995 for non-Aboriginal mothers. 8 ....... MothersMothersMothersMothersMothers.......... DemographyDemographyDemographyDemographyDemography Age of mother Percent 20 16 4 8 12 Non-Aboriginal Aboriginal 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 7: Proportion of mothers aged 35 years and over, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 4.3 3.1 4.1 5.4 3.9 3.7 4.5 4.6 4.7 3.5 Non-Aboriginal 7.3 7.7 7.5 8.2 10.0 11.2 12.0 11.0 12.1 12.4 Total 6.3 6.1 6.2 7.1 7.9 8.7 9.4 8.8 9.6 9.4 • High maternal age is a risk factor for gestational diabetes, hypertension and renal disease. In addition, older mothers are more likely to have multiple pregnancies or suffer chromosomal abnormalities. Both maternal and perinatal mortality also increase with maternal age. • The proportion of Aboriginal mothers aged 35 years and over remained stable throughout the period. • The proportion of non-Aboriginal mothers who were 35 years and over at delivery increased throughout the period from 7% in 1986 to 12% in 1995. • In 1986, the proportion of non-Aboriginal mothers who were 35 years and over was 1.7 times the proportion for Aboriginal mothers. In 1995, that relative difference had increased to 3.5. 9 ....... MothersMothersMothersMothersMothersAntenatal Gestation Weeks 39 Aboriginal Non-Aboriginal 37 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 8: Average duration of pregnancy (in weeks), NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Weeks Aboriginal 38.4 38.9 38.4 38.5 38.3 38.5 38.4 38.5 38.5 38.5 Non-Aboriginal 39.2 39.4 39.2 39.3 39.2 39.2 39.2 39.3 39.2 39.1 Total 38.9 39.3 38.9 39.0 38.9 39.0 38.9 39.1 39.0 38.9 • Duration of pregnancy (or gestation age) is defined as the difference between the date of the mother's last menstrual period (LMP) and the date of delivery of the baby. If the LMP date is not available, then gestation is estimated from clinical grounds which include ultrasound, foetal size and other parameters. • The average duration of pregnancy with both Aboriginal and non-Aboriginal mothers does not appear to have changed over the decade under study. The mean duration over the period was 38.4 weeks for Aboriginal mothers and 39.2 weeks for non-Aboriginal mothers. • It is not certain, however, that the relatively shorter average duration of Aboriginal pregnancies is real. Due to problems associated with recall of the LMP, the duration of Aboriginal pregnancies is often based on clinical grounds. As Aboriginal infants are more likely to be 'small for gestational age', the duration of pregnancy may be underestimated; therefore interpretation of these statistics must be made with this in mind. 10 ....... MothersMothersMothersMothersMothersAntenatal Gestation Percent 20 18 16 12 14 10 8 6 Aboriginal Non-Aboriginal 4 2 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 9: Proportion of mothers delivering prematurely, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 14.4 11.5 14.7 13.9 14.6 13.1 15.0 12.0 12.8 12.0 Non-Aboriginal 5.7 5.1 6.8 6.6 6.4 6.7 6.6 5.6 6.4 6.1 Total 8.6 7.4 9.8 9.6 9.2 8.8 9.5 7.8 8.6 8.1 • Preterm deliveries are those which occur before 37 completed weeks gestation. Risk factors associated with preterm delivery include smoking, maternal education, low socioeconomic status, low pre-pregnancy weightmaternal age less than 18 years or 40 years and over. • Premature labour, premature rupture of membranes, maternal illness and fetal distress or demise are immediate causes of preterm delivery. Infants born prematurely are at greater risk of neonatal complications and death. • Causes of premature labour include infection, antepartum haemorrhage, multiple pregnancy, uterine and cervical abnormalities and foetal malformation. • The proportion of mothers delivering preterm was higher among Aboriginal mothers than non- Aboriginal mothers, throughout the study period; however this should be interpreted taking into account what has been previously noted regarding the measurement of gestation (see page 10). There has been little change during the study period. 11 Mothers Antenatal Antenatal care in the first trimester of pregnancy Percent 15 20 25 30 35 40 45 Non-Aboriginal Aboriginal 10 5 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 10: Proportion of mothers who received antenatal care in the first trimester of their pregnancy, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 12.4 12.8 13.4 15.3 20.1 19.9 24.5 21.8 23.6 25.3 Non-Aboriginal 47.8 47.1 48.4 47.6 43.2 47.3 38.7 34.6 33.0 46.4 Total 36.1 34.9 35.3 34.6 35.3 38.1 33.9 30.3 29.8 39.3 Note: Data in italics in the table refer to years for which there was a high proportion of unreported data, and have been left out of the graph. • Gestational age at first visit for antenatal care is often used as an indicator of adequate and timely antenatal care. The proportion of women who present for care early in their pregnancy (before 13 weeks) is a useful marker of access to antenatal services. • The proportion of non-Aboriginal mothers who received antenatal care in the first trimester appears to have remained stable over the study period. Analysis of these data has been difficult since 1992 because a high proportion of forms were returned with this information missing. • The proportion of Aboriginal mothers receiving antenatal care in the first trimester of their pregnancy increased throughout the decade from 12% in 1986 to at least 25% in 1995. This might be due to an increase in culturally appropriate antenatal care services available to Aboriginal women. • As can be seen opposite the proportion of women receiving antenatal care in the first trimester is higher for both Aboriginal and non- Aboriginal mothers in Katherine and Alice Springs Urban regions. 12 Mothers Antenatal Antenatal care in the first trimester of pregnancy by district Percent Percent Darwin Rural Darwin Urban 100 100 80 80 60 60 Non-Aboriginal 40 40 20 20 Aboriginal 0 0 1985 1987 1989 1991 1993 1995 1985 1987 1989 1991 1993 1995 Percent East Arnhem Percent Katherine 100 80 60 40 20 0 100 80 60 40 20 0 1985 1987 1989 1991 1993 1995 1985 1987 1989 1991 1993 1995 Percent Percent Barkly Alice Springs Urban 100 80 60 40 20 0 100 80 60 40 20 0 1985 1987 1989 1991 1993 1995 1985 1987 1989 1991 1993 1995 Percent Alice Springs Rural 100 80 60 40 20 0 Note: Where there was more than 10% 'unreported', the data were considered unreliable and were omitted from the graphs. Refer to table A1 page 54 of the appendix to view the data pertaining to these graphs. 1985 1987 1989 1991 1993 1995 13 Mothers Antenatal procedures Ultrasound 0 10 20 30 40 50 60 70 80 90 100 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Non-Aboriginal Aboriginal Table 11: Proportion of mothers who received ultrasound during their antenatal care, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 62.6 65.0 81.3 n.a. 88.2 87.8 90.3 82.1 84.0 88.1 Non-Aboriginal 85.5 88.8 91.1 n.a. 96.3 95.4 96.1 90.6 89.0 90.7 Total 77.9 80.3 87.4 n.a. 93.5 92.9 94.1 87.7 87.3 89.8 Note: Data were not available for 1989. The 1989 value on the graph was interpolated from the 1988 and 1990 values. • Foetal ultrasound is used during pregnancy to estimate gestation age, assess placental position and foetal well-being and diagnose foetal abnormality. • In the NT, it is recommended that all pregnant women have an ultrasound, ideally at 18 weeks gestation. The gestational age at which ultrasound was performed was not recorded. • The proportion of mothers who undergo ultrasound is an indicator of both acceptance of ultrasound as a useful procedure and access to ultrasound services. • The proportion of both Aboriginal and non- Aboriginal mothers who underwent ultrasound increased until 1992. The reason for the apparent decline between 1992 and 1993 is not known. • 90% of mothers had an ultrasound in 1995, with little difference between Aboriginal and non- Aboriginal mothers. 14 Mothers Antenatal procedures Amniocentesis for older mothers Percent 40 35 Non-Aboriginal 10 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 15 20 25 30 0 5 Aboriginal Table 12: Proportion of mothers aged 35 years and over who received an amniocentesis test during their antenatal care, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 0.0 0.0 2.3 0.0 4.5 0.0 3.8 5.6 1.9 0.0 Non-Aboriginal 31.0 22.6 22.0 13.4 20.3 26.8 22.7 23.9 18.7 18.8 Total 24.0 18.5 17.1 9.3 17.6 22.9 19.6 20.6 15.9 16.5 • Amniocentesis involves the aspiration and examination of the amniotic fluid and cells which surround the foetus. This procedure is usually performed early in pregnancy to diagnose chromosomal abnormalities, but may also be used to detect malformations of the central nervous system or to assess maturity. • Indications for amniocentesis include maternal age of 35 years and over, a family history of a diagnosable genetic disease or other positive findings such as a raised serum alphafetoprotein. • The proportion of women who underwent amniocentesis fluctuated from year to year with 2.4% of all mothers who confined having the procedure. The corresponding figure in mothers 35 years of age and over was 18.4%. • There was a large difference between the proportion of Aboriginal and non-Aboriginal women undergoing the procedure with only 2% of Aboriginal mothers aged 35 years and over having amniocentesis compared with 22% of non-Aboriginal mothers. This may reflect cultural differences or difficulties with access. 15 Mothers Antenatal medical conditions Anaemia Percent Aboriginal 8 10 12 14 16 18 2 4 Non-Aboriginal 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 13: Proportion of mothers who were diagnosed with anaemia during their pregnancy, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 8.2 12.1 13.6 13.0 16.7 13.8 15.5 11.9 18.8 18.9 Non-Aboriginal 1.3 2.0 2.3 2.6 3.1 1.9 2.5 2.1 3.6 3.0 Total 3.6 5.6 6.6 6.8 7.7 5.9 6.9 5.4 8.7 8.3 • During the decade under study there was no strict definition of 'anaemia'; rather it was deemed to be present if the diagnosis was made, documented in the record and noted by the midwife. Definitions in various situations may therefore have varied. • In the NT, anaemia in pregnancy is likely to be due to iron or folate deficiency. Aboriginal mothers are more suceptible to anaemia during pregnancy because of their relatively poor nutrition and the presence of endemic illnesses. • In recent years the prevalence of documented anaemia in pregnancy has been increasing in both Aboriginal and non-Aboriginal mothers. This increase may be due to improved access to antenatal care and surveillance rather than an increase in true prevalence. Nevertheless, the prevalence in Aboriginal mothers is high by any standard. 16 We would like to hear from youThe Epidemiology Branch of Territory Health Services values your opinion, constructive criticisms and suggestions for improving the way that we provide information on the health status and the factors that affect health in the Northern Territory. Our aim is to inform the community, policy makers and service providers about the state of health and about those factors that influence health in the Northern Territory. In addition to striving to provide scientifically sound information, the Epidemiology Branch aims to produce this information in a form that is easy to read and understand, and to make the information widely available. In future, all our publications will be available in electronic form with a limited number of printed copies. If you wish to remain on our mailing list, please take a moment to photocopy the questionnaire on page 32 of this report, complete it and return to us. Thank you for your cooperation. We would like to hear from youThe Epidemiology Branch of Territory Health Services values your opinion, constructive criticisms and suggestions for improving the way that we provide information on the health status and the factors that affect health in the Northern Territory. Our aim is to inform the community, policy makers and service providers about the state of health and about those factors that influence health in the Northern Territory. In addition to striving to provide scientifically sound information, the Epidemiology Branch aims to produce this information in a form that is easy to read and understand, and to make the information widely available. In future, all our publications will be available in electronic form with a limited number of printed copies. If you wish to remain on our mailing list, please take a moment to photocopy the questionnaire on page 32 of this report, complete it and return to us. Thank you for your cooperation. 17 ....... MothersMothersMothersMothersMothers............................ Antenatal medical conditionsAntenatal medical conditionsAntenatal medical conditionsAntenatal medical conditionsAntenatal medical conditions Gestational diabetes Percent 10 9 8 7 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1 2 3 4 5 6 Aboriginal Non-Aboriginal Table 14: Proportion of 20-29 year old mothers diagnosed with gestational diabetes, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 2.5 3.0 3.3 3.6 5.2 5.2 6.3 5.3 6.1 4.1 Non-Aboriginal 0.8 1.2 1.5 1.2 2.4 2.5 3.4 3.5 3.0 2.3 Total 1.3 1.8 2.2 2.2 3.4 3.5 4.4 4.1 4.1 3.0 • Diabetes in pregnancy can be pre-existing or can develop during pregnancy. The information presented in the graphs and tables on this and the next page refers to gestational diabetes. As the prevalence of diabetes increases with age, the data have been presented separately for the maternal age groups: 20–29 years this page and 30 years and over on the next page. Different scales are used for each graph. • Infants of mothers who have pre-existing diabetes have an increased risk of fetal malformation, foetal death, respiratory distress syndrome and other neonatal metabolic disturbances. Less than one per cent of mothers had pre-existing diabetes, with little variation during the study period. • The proportion of Aboriginal mothers with gestational diabetes was substantially higher than that of non-Aboriginal mothers. There was a steady increase for both groups until the early 1990s after which the proportions appeared to be declining. The reason for the increase is unclear and may be related to an improvement in the ascertainment of cases. 18 ....... MothersMothersMothersMothersMothers............................ Antenatal medical conditionsAntenatal medical conditionsAntenatal medical conditionsAntenatal medical conditionsAntenatal medical conditions Gestational diabetes Percent 5 10 15 20 Aboriginal Non-Aboriginal 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 15: Proportion of mothers aged 30 years and over with gestational diabetes, NT, 1986– 95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 11.8 6.0 9.7 12.7 13.0 21.4 18.9 9.7 15.6 12.2 Non-Aboriginal 1.6 3.0 1.5 1.6 3.9 4.9 6.7 5.4 5.2 5.4 Total 3.5 3.6 3.2 4.2 5.3 7.1 8.8 6.1 6.7 6.4 • Babies of mothers with diabetes are also at risk of high birth weight and associated complications such as shoulder dystocia, birth trauma and asphyxia. • The proportion of mothers with gestational diabetes increased in both Aboriginal and non- Aboriginal mothers until 1992, after which it declined slightly. The reason for the initial increase is unknown and may be related to an improvement in case detection. • The proportion of Aboriginal mothers with gestational diabetes has been consistently greater than the proportion of non-Aboriginal mothers with gestational diabetes. • Both Aboriginal and non-Aboriginal mothers aged 30 years and over had substantially higher rates of gestational diabetes compared with those aged 20–29 years. 19 Mothers Antenatal obstetric complications Pre-eclampsia Percent 6 8 Aboriginal Non-Aboriginal 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 16: Proportion of mothers who were diagnosed with pre-eclampsia, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 6.8 7.6 9.4 8.5 8.0 7.1 7.8 7.9 7.0 6.8 Non-Aboriginal 4.9 5.6 5.7 7.3 5.5 5.3 5.7 5.6 5.5 5.4 Total 5.6 6.3 7.1 7.8 6.4 5.9 6.4 6.4 6.0 5.9 • Pre-eclampsia is a serious complication of pregnancy, and is a major cause of maternal and infant mortality and morbidity. It is a systemic disease clinically characterised by increasing blood pressure, the development of proteinuria and at times the onset of oedema. • Risk factors for pre-eclampsia include primiparity (first pregnancy), pre-existing hypertension, twin pregnancy and auto-immune disease. • Although knowledge about the pathophysiology has increased in recent years, the cause of preeclampsia remains unknown. A genetic predisposition is likely, but no environmental factors have been confirmed as causative agents. • During the decade under study, there was little variation in the prevalence of pre-eclampsia, although it was more prevalent in Aboriginal mothers. 20 Mothers Antenatal obstetric complications Intra-uterine growth retardation 0 3 6 9 12 15 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Non-Aboriginal Aboriginal Table 17: Proportion of mothers who were diagnosed with IUGR, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal n.a. 11.9 11.4 6.9 9.2 5.3 8 3.3 2.7 4.2 Non-Aboriginal n.a. 5.2 5.3 3 3 3.2 3.4 1.5 1.9 1.9 Total n.a. 7.6 7.6 4.6 5.1 3.9 5 2.1 2.2 2.7 Note: Data for the year 1986 were unreliable and were not included in either the graph or in the table. • Intra-uterine growth retardation (IUGR) is a reflection of poor placental function. Its risk factors include poor maternal nutrition, high alcohol intake, smoking, pre-eclampsia, congenital malformation and intra-uterine infection. • IUGR was not strictly defined for the purposes of this data collection; rather it was deemed to be present if the diagnosis was made, documented in the record and noted by the midwife. • Due to this imprecise definition these figures are difficult to interpret, nevertheless it is noteworthy that the recorded incidence of IUGR has declined in both Aboriginal and non- Aboriginal confinements during the study period. • This fall may be due to improved maternal health, but it also might reflect changes in diagnosis patterns or documentation procedures. 21 Mothers Labour, delivery and puerperium Induction of labour Percent Non-Aboriginal 10 15 20 Aboriginal 5 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 18: Proportion of mothers who underwent induction of labour, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 10.4 9.9 10.3 10.4 10.1 10.6 14.4 13.4 12.8 12.8 Non-Aboriginal 20.5 18.7 16.7 17.5 18.6 22.4 23.6 23.2 20.9 23.1 Total 17.2 15.6 14.3 14.6 15.7 18.4 20.5 19.8 18.2 19.7 • Induction of labour is indicated when the benefits of delivery outweigh the risks of continuing the pregnancy and the maternal and foetal conditions for induction are appropriate. • Indications for inducing labour include preeclampsia, chorioamnionitis, foetal death, placental abruption, intra-uterine growth retardation, foetal distress, prolonged gestation and maternal medical illnesses. • Induction rates fluctuated during the study period, with a general upward trend. The non- Aboriginal rate was nearly twice that of Aboriginal mothers. • The data collection did not allow for analysis of induction rates by indication during the study period, but will do so from 1996. 22 Mothers Labour, delivery and puerperium Induction of labour by hospital Royal Darwin Hospital 0 10 20 30 40 1985 1987 1989 1991 1993 Percent Aboriginal Non-Aboriginal 1995 Katherine Hospital 0 10 20 30 40 1985 1987 1989 1991 1993 Percent 1995 Tennant Creek Hospital 0 10 20 30 40 1985 1987 1989 1991 1993 Percent 1995 Alice Springs Hospital 0 10 20 30 40 1985 1987 1989 1991 1993 Percent 1995 0 10 20 30 40 1985 Percent Darwin Private Hospital 1987 1989 1991 1993 1995 0 10 20 30 40 1985 Percent Gove District Hospital 1987 1989 1991 1993 1995 • Induction rates by hospital are presented here for the period 1986–95. It is important to bear in mind that numbers in the regional hospitals are small and wide fluctuations from year to year can be expected. • The data from the Darwin Private Hospital were not reported until 1990. There were too few Aboriginal mothers to render the statistics meaningful so they were not presented. Refer to table A2 page 54 of the appendix to view the data pertaining to these graphs. 23 Mothers Labour, delivery and puerperium Caesarean section Percent Aboriginal 15 20 25 Non-Aboriginal 10 5 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 19: Proportion of mothers who underwent a Caesarean section, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 17.8 18.1 16.9 16.5 18.0 16.3 20.2 21.6 22.6 24.5 Non-Aboriginal 13.5 15.6 13.1 13.0 15.2 14.4 17.1 20.3 19.8 18.9 Total 14.9 16.5 14.5 14.4 16.1 15.1 18.1 20.8 20.8 20.7 • Delivery is made by Caesarean section when the risks to mother or foetus of vaginal delivery are considered to be outweighed by the benefits of surgery. • Caesarean section can be 'elective', where the indications for surgery exist prior to the onset of labour (such as a contracted pelvis), or 'emergency', where complications arise during labour (such as a prolapsed cord). • The Caesarean section rate rose in the Northern Territory during the study period to be 20.7% of confinements in 1995. It was consistently higher in Aboriginal mothers. • The figures for 1988 and 1989 were incomplete due to a lack of data from the Darwin Private Hospital and should be interpreted with caution. 24 Mothers Labour, delivery and puerperium Caesarean section by hospital Percent Royal Darwin Hospital 30 25 20 15 Aboriginal 10 5 0 1985 Percent 30 25 Non-Aboriginal 1987 1989 1991 1993 1995 Katherine Hospital 20 15 10 5 0 1985 1987 1989 1991 1993 1995 Percent Alice Springs Hospital 30 25 20 15 10 5 0 1985 1987 1989 1991 1993 1995 Refer to table A3 page 55 of the appendix to view the data pertaining to these graphs. Percent 30 25 20 15 10 5 0 1987 Percent 30 25 20 15 10 5 0 Darwin Private Hospital 1989 1991 1993 1995 Gove District Hospital 1985 1987 1989 1991 1993 1995 • Caesarean section rates for each hospital are presented here where there was an average of more than 10 caesarean sections per year. Tennant Creek Hospital had very few caesarean sections and so was not included. • Rates were highest in the major hospitals with rates for Aboriginal women often exceeding 20%, and increasing. • When interpreting the variation in caesarean section rates between hospitals it should be born in mind that the larger hospitals attract the high risk confinements together with some elective Caesarean sections from the smaller hospitals and will therefore have disproportionately higher rates. 25 Mothers Labour, delivery and puerperium Instrumental delivery 0 1 2 3 4 5 6 7 8 9 10 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Forceps - Aboriginal Forceps - Non-Aboriginal Ventouse - Aboriginal Ventouse - Non-Aboriginal Table 20: Proportion of mothers who underwent intrumental delivery, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Forceps delivery: Aboriginal 5.5 5.1 4.0 3.4 4.6 5.1 5.4 3.8 3.1 2.7 Non-Aboriginal 9.5 7.0 7.2 6.8 6.6 7.6 7.5 5.0 4.1 5.6 Total 8.2 6.4 6.0 5.5 5.9 6.8 6.8 4.6 3.8 4.6 Ventouse delivery: Aboriginal 1.8 2.3 2.5 2.5 2.0 1.7 1.9 2.0 1.6 0.8 Non-Aboriginal 0.8 0.7 1.6 1.6 1.0 1.1 1.9 1.6 1.9 1.5 Total 1.1 1.3 1.9 2.0 1.3 1.3 1.9 1.7 1.8 1.2 • Instrumental delivery is used to shorten the second stage of labour when there is evidence of foetal distress or maternal exhaustion. • Delivery can be achieved through the use of obstetric forceps, or by vacuum extraction (ventouse). • Overall, the proportion of mothers undergoing instrumental delivery fell during the study period; this fall was mainly due to a change in the rate of forceps delivery. • Complications which may have arisen from instrumental delivery were not recorded. 26 Mothers Labour, delivery and puerperium Retained placenta Percent 5 4 2 3 Aboriginal Non- Aboriginal 1 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 21: Proportion of mothers who had a retained placenta, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 7.6 3.1 2.5 2.4 3.7 2.2 3.2 1.5 1.9 1.5 Non-Aboriginal 5.2 2.6 3.0 2.4 2.4 2.3 2.4 1.6 2.9 2.0 Total 6.0 2.8 2.8 2.4 2.8 2.3 2.7 1.6 2.5 1.8 Note: Data for the year 1986 were unreliable and were not included in the graph. • Retention of the placenta is a complication of delivery which requires anaesthesia and operative removal. • Retained placenta is usually defined as an undelivered placenta one hour after delivery. • There appears to be a downward trend in the proportion of confinements with retained placenta over the study period. • Over the recent past, the incidence in non- Aboriginal mothers has been higher than that of Aboriginal mothers. 27 Mothers Labour, delivery and puerperium Post-partum haemorrhagic complications 0 1 2 3 4 5 6 7 8 9 10 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal Non-Aboriginal Table 22: Proportion of mothers who had post-partum haemorrhage, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal n.a. 7.4 7.2 7.8 7.0 7.2 8.4 7.0 9.8 8.6 Non-Aboriginal n.a. 3.5 4.5 4.4 3.6 3.5 4.6 4.3 5.9 4.7 Total n.a. 4.9 5.5 5.8 4.7 4.8 5.9 5.2 7.2 6.0 Note: Data for 1986 were unreliable and therefore not used in the graph or table. • Post-partum haemorrhage is usually defined as more than 600mls of blood loss from the birth canal within the first 24 hours after delivery. • The major causes of post-partum haemorrhage are a retained placenta, trauma, uterine atony or a bleeding disorder. The risk increases with increasing parity. • The proportion of confinements with a postpartum haemorrhage was higher in Aboriginal mothers than in non-Aboriginal mothers. There was a gradual increase in both groups during the study period. 28 Mothers Health service use Confinements out of hospital Percent 0 2 4 6 8 10 Non-Aboriginal Aboriginal 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 23: Proportion of mothers who delivered out of hospital, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 9.7 11.0 9.7 8.4 9.1 7.0 5.7 6.1 5.2 4.5 Non-Aboriginal 0.3 0.4 0.3 0.1 0.3 0.5 0.5 0.5 0.4 0.9 Total 3.4 4.2 3.9 3.5 3.3 2.7 2.3 2.4 2.0 2.1 • These statistics include both planned homebirths and other deliveries which occurred prior to arrival in hospital. The proportion of babies born out of hospital has been decreasing during the decade under study. • This decrease has been exclusively among Aboriginal non-hospital births, which have decreased from a high of 11.0% in 1987 to 4.5% in 1995. This may reflect improved access to hospital or more culturally appropriate birthing practises. • The statistics relating to non-Aboriginal births should be interpreted with caution because it is likely that a substantial number of these births were not reported to the Midwives’ Data Collection. The proportions shown are likely to be under-estimates. There is some evidence nevertheless to suggest that non-hospital births are increasing in the non-Aboriginal population. 29 Mothers Hospital service use Average duration of postnatal hospital stay Number of days 10 9 8 7 6 4 5 Aboriginal 3 Non-Aboriginal 2 1 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 24: Average duration of mothers' postnatal hospital stay (in days), NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Days Aboriginal 5.6 5.3 5.3 4.9 5.0 5.0 4.9 4.4 4.5 4.4 Non-Aboriginal 4.4 4.3 4.1 3.9 4.1 4.0 3.9 4.0 3.9 3.6 Total 4.7 4.7 4.5 4.3 4.4 4.3 4.2 4.1 4.1 3.9 Note: Average length of stay was calculated using the geometric mean • The average length of mothers’ postnatal stay decreased during the study period for both Aboriginal and non-Aboriginal mothers. The average length of stay for Aboriginal mothers fell by 20.5% from 5.6 to 4.4 days,and for non- Aboriginal mothers by 16.7% from 4.4 to 3.6 days. • Aboriginal mothers stayed in hospital longer than non-Aboriginal mothers, although the difference between them became less with time. • Geometric mean was used for summary data and comparisons here because the distribution of length of stay data approximates log normal. 30 Mothers Hospital service use Average duration of postnatal stay by hospital Days Royal Darwin Hospital 7 6 Aboriginal 5 4 3 Non-Aboriginal 2 1 0 1985 1987 1989 1991 1993 1995 Days Gove District Hospital 7 6 5 4 3 2 1 0 1985 1987 1989 1991 1993 1995 Days Tennant Creek Hospital 7 6 5 4 3 2 1 0 1985 1987 1989 1991 1993 1995 Days Alice Springs Hospital 7 6 5 4 3 2 1 0 1985 1987 1989 1991 1993 1995 • The average length of mothers’ postnatal stay decreased in all hospitals during the ten year period from 1986–95. • Aboriginal mothers had a longer average postnatal stay than non-Aboriginal mothers in all hospitals apart from Tennant Creek and Darwin Private Hospitals. • When comparing average length of stay between hospitals it should be born in mind that the larger hospitals attract the high risk confinements and will therefore have disproportionately longer length of stay. 0 1 2 3 4 5 6 7 1985 1987 1989 1991 1993 1995 Days Katherine Hospital 0 1 2 3 4 5 6 7 1985 1987 1989 1991 1993 1995 Days Darwin Private Hospital Refer to table A4 page 55 of the appendix to view the data pertaining to these graphs. 31 Your comments, pleas. Please mail your comments to: Territory Health Services, Epidemiology Branch, NT Midwives Data Collection, PO Box 40596 Casuarina NT 0810 alternatively you can e-mail to: epidemiology@nt.gov.au A. Can you please describe yourself. For example, are you a midwife, a mother or other member of the public, an Aboriginal health worker, an obstetrician, a policy analyst, a student or other category? ........................................................................................................................................................ B. Can you describe your main occupation (tick more than one box if necessary) Planning and delivering health services Policy development work Conducting research and analysis Other ........................................... C. How did you find the format of this report? Easy to follow Difficult to follow Any comments: ............................................................................................................................... D. Did you find the report informative? Yes No Any comments: ............................................................................................................................... E. What contents changes would you like to see to the report to make it more informative? ........................................................................................................................................................ ........................................................................................................................................................ F. Do you wish to be included on our notification mailing list for future reports? Yes No Your name: .................................................. Your e-mail address: Your postal address: ............................................... ................................................. .................................................. ................................................. 32 . . ...... BabiesBabiesBabiesBabiesBabies Demography • Indigenous status Morbidity • Foetal distress • Birthweight less than 2,500 grams • Birthweight of 4,000 grams and over • Average birthweight • Average birthweight by district • APGAR scores less than seven • Neonatal infection Health service use • Hospital of birth Mortality • Foetal deaths • Neonatal deaths • Perinatal deaths • Infant deaths Babies Demography Indigenous Status Number of livebirths 2500 2000 1500 1000 500 0 Aboriginal Non-Aboriginal 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 25: Number and proportion of total and livebirths, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Total births: Number Aboriginal 1059 1119 1080 1114 1131 1154 1196 1178 1157 1176 Non-Aboriginal 2147 2030 1785 1649 2192 2299 2355 2276 2283 2361 Total 3206 3149 2865 2763 3323 3453 3551 3454 3440 3537 Percent Aboriginal 33.0 35.5 37.7 40.3 34.0 33.4 33.7 34.1 33.6 33.2 Non-Aboriginal 67.0 64.5 62.3 59.7 66.0 66.6 66.3 65.9 66.4 66.8 Livebirths: Number Aboriginal 1037 1089 1048 1089 1108 1131 1174 1154 1139 1157 Non-Aboriginal 2135 2013 1771 1641 2163 2278 2334 2262 2264 2344 Total 3172 3102 2819 2730 3271 3409 3508 3416 3403 3501 Percent Aboriginal 32.7 35.1 37.2 39.9 33.9 33.2 33.5 33.8 33.5 33.0 Non-Aboriginal 67.3 64.9 62.8 60.1 66.1 66.8 66.5 66.2 66.5 67.0 • There has been a steady increase in the number of total births (stillbirths plus livebirths) and livebirths in the Northern Territory, reflecting an increase in the number of women of childbearing age in the population. • The apparent decline in non-Aboriginal births in 1988 and 1989 is spurious. It reflects the transfer of new births to the Darwin Private Hospital which opened in 1987. Data from the Private Hospital were not available to the Midwives Collection until 1990. 34 Babies Morbidity Foetal distress Percent 20 18 8 10 12 14 16 Aboriginal Non-Aboriginal 6 4 2 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 26: Proportion of babies who suffered from foetal distress at delivery, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 8.7 11.5 10.6 12.9 15.6 14.1 13.9 11.9 13.5 12.0 Non-Aboriginal 9.4 8.7 10.5 10.6 11.4 12.0 11.4 7.4 10.8 9.1 Total 9.2 9.7 10.5 11.5 12.8 12.7 12.2 8.9 11.7 10.1 • The stress of the birth process to the foetus can contribute to intra-partum and post-partum foetal morbidity and mortality. • Foetal distress is diagnosed through use of the cardiotocograph, which monitors foetal heart beat patterns and their relationship with uterine contractions. • During the decade under study 'foetal distress' was not strictly defined; rather it was deemed to be present if the diagnosis was made, documented in the record and noted by the midwife. Definitions in various situations may therefore have varied. • The proportion of deliveries associated with foetal distress appeared to increase until 1990, after which it fell slightly. The proportion was higher among Aboriginal deliveries. 35 Babies Morbidity Birthweight Percent 20 18 Non-Aboriginal 4 2 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 6 8 10 12 14 16 Aboriginal Table 27: Proportion of livebirths with birthweight of less than 2,500 grams, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 15.0 14.6 15.6 12.5 14.9 13.5 14.9 12.0 13.2 12.6 Non-Aboriginal 6.2 5.9 5.9 5.6 6.2 7.0 7.5 6.0 5.8 5.7 Total 9.1 8.9 9.5 8.3 9.2 9.2 10.0 8.0 8.3 8.0 • Low birth weight is associated with increased risk of neonatal morbidity and mortality. • Factors which predispose to low birth weight include prematurity, poor maternal nutrition, high alcohol intake, smoking, pre-eclampsia, congenital malformation and intra-uterine infection. • The proportion of non-Aboriginal babies with birthweight below 2,500 grams did not change significantly (p=0.99). In contrast, the proportion of Aboriginal babies below 2,500 grams birthweight decreased significantly throughout the study period (p=0.022 for linear trend). • It is unlikely that this improvement is due to an increase in the propensity for women to identify as Aboriginal (with more women with higher birthweight babies being classified as Aboriginal), because the absolute numbers of Aboriginal low birthweight infants also fell over time. 36 Babies Morbidity Birthweight Percent Non-Aboriginal 4 6 8 10 Aboriginal 2 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 28: Proportion of livebirths with birthweight of 4,000 grams and over, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 5.5 4.9 4.0 4.7 4.4 5.0 4.9 5.6 5.5 5.5 Non-Aboriginal 9.0 9.4 9.2 10.0 8.8 8.9 8.6 8.6 8.9 10.5 Total 7.9 7.8 7.3 7.9 7.3 7.6 7.3 7.6 7.7 8.9 • Babies with a high birthweight are more likely to suffer birth trauma, shoulder dystocia and asphyxia. • Babies born to mothers with diabetes are more likely to have a birthweight greater than 4000 grams, and to develop subsequent neonatal jaundice, respiratory distress syndrome, haemorrhagic disease and congenital malformation. • The proportion of Aboriginal babies with birthweight greater than 4000 grams did not change significantly during the study period (p=0.27). Likewise the proportion of non- Aboriginal babies did not change (p=0.99). 37 Babies Morbidity Average birthweight Grams 3400 Non-Aboriginal 3000 2950 2900 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 3050 3100 3150 3200 3250 3300 3350 Aboriginal Table 29: Average birthweight of livebirths (in grams), NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Grams Aboriginal 3023 3057 3039 3067 3033 3056 3052 3097 3111 3123 Non-Aboriginal 3305 3331 3304 3336 3306 3292 3289 3314 3319 3348 Total 3213 3235 3206 3229 3214 3214 3210 3241 3250 3273 • Birthweight is influenced by many factors including gestational age, socio-economic status, maternal weight, maternal nutrition and disease, smoking, alcohol, parity and the baby’s sex. • Comparisons of birthweight between two groups should take these factors into account; however this type of analysis is not within the scope of this report. • In the ten years to 1995 the mean birthweight of Aboriginal babies increased significantly (p<0.001 for linear trend). Mean birthweight rose by 85 grams, which was 30.0% of the difference between Aboriginal and non- Aboriginal birthweights in 1986. • The mean birthweight of non-Aboriginal babies did not vary significantly (p=0.30). 38 Babies Morbidity Average birthweight by district Grams Grams Darwin Urban Darwin Rural 3750 3750 3500 3500 Non-Aboriginal 3250 3250 Aboriginal 3000 3000 2750 2750 1985 1987 1989 1991 1993 1995 1985 1987 1989 1991 1993 1995 Grams 3750 3500 3250 3000 2750 Grams Katherine East Arnhem 3750 3500 3250 3000 2750 1985 1987 1989 1991 1993 1995 1985 1987 1989 1991 1993 1995 Grams Grams Barkly Alice Springs Urban 3750 3500 3250 3000 2750 3750 3500 3250 3000 2750 1985 1987 1989 1991 1993 1995 1985 1987 1989 1991 1993 1995 Grams Alice Springs Rural • The average birthweight of non-Aboriginal 3750 3500 3250 3000 2750 babies has been consistently greater than that of Aboriginal babies for each of the seven health districts. Refer to table A5 page 56 of the appendix to view the data pertaining to these graphs. 1985 1987 1989 1991 1993 1995 39 Babies Morbidity Apgar scores less than 7 Percent 5 10 15 20 25 APGAR score at 1 minute APGAR score at 5 minutes Aboriginal Non-Aboriginal Aboriginal Non-Aboriginal 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 30: Proportion of livebirths with APGAR scores of less 7 at one and five minutes, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 At one minute: Percent Aboriginal 28.8 26.7 22.5 19.7 26.2 20.1 20.4 21.9 24.1 20.4 Non-Aboriginal 17.9 18.9 16.6 17.6 18.6 15.8 15.5 14.9 16.8 14.5 Total 21.5 21.7 18.8 18.5 21.2 17.3 17.1 17.3 19.3 16.5 At five minutes: Percent Aboriginal 9.1 5.4 4.5 4.9 6.6 4.2 4.3 4.2 6.8 4.8 Non-Aboriginal 1.7 2.2 1.9 2.4 2.3 2.4 2.1 1.9 2.2 1.9 Total 4.1 3.3 2.9 3.4 3.7 3.0 2.8 2.7 3.7 2.9 • Apgar scores give an indication of foetal wellbeing after delivery and reflect the effects of the birth process on the physiology of the newborn. Five parameters (heart rate, respiration, colour, tone and response to stimuli) are scored, at one and five minutes after delivery, as either zero, one or two; these are summed giving a total out of a maximum score of ten. • Between 1986 and 1995, there was a downward trend in the proportion of low Apgar scores at one minute, for both Aboriginal and non- Aboriginal neonates. • The proportion of neonates with low Apgar scores was always higher in the Aboriginal group. 40 Babies Morbidity Neonatal infection Percent 10 9 2 3 4 5 6 7 8 Aboriginal Non-Aboriginal 1 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 31: Livebirths who developed neonatal infection, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Percent Aboriginal 4.6 5.5 8.1 8.5 8.5 6.3 5.6 4.3 5.4 3.9 Non-Aboriginal 2.3 1.8 4.9 5.2 5.5 5.7 3.5 2.8 3.6 3.5 Total 3.0 3.1 6.1 6.5 6.5 5.9 4.2 3.3 4.2 3.6 • Infection in the neonatal period is a major cause of morbidity and mortality in the fetus. • Risk factors for neonatal infection include poor ante-natal care, pre-existing genital tract infection, or prolonged rupture of membranes. • Neonatal infection was not strictly defined for the purposes of this data collection; rather it was deemed to be present if the diagnosis was made, documented in the record and noted by the midwife. • Although these data should be interpreted with caution, a fall in the proportion of neonates with infection from the late 1980s was noted. 41 Babies Health service use Hospital of birth Births 225 Royal Darwin Hospital 0 400 800 1200 1600 1985 1987 1989 1991 1993 1995 Births Aboriginal Non-Aboriginal Alice Springs Hospital 0 400 800 1200 1600 1985 1987 1989 1991 1993 1995 Births Katherine Hospital 200 175 150 125 100 75 50 25 0 1985 Births 225 200 175 150 125 100 75 50 1987 1989 1991 1993 1995 Tennant Creek Hospital 25 0 1985 1987 1989 1991 1993 1995 Births Darwin Private Hospital 1600 1200 800 400 0 1985 1987 1989 1991 1993 1995 • Data from the three major hospitals are presented here on the same scale. • The Darwin Private Hospital provided obstetric services from 1987, causing a fall in deliveries at Royal Darwin Hospital. However, complete data for the Darwin Private Hospital were not available to the Midwives Collection until 1990. Births Gove District Hospital 225 200 175 150 125 100 75 50 25 0 1985 1987 1989 1991 1993 1995 • Data from the three regional hospitals are presented here on the same scale. • In the smaller hospitals, numbers of deliveries might fluctuate with varying staff resources, or population movements such as an influx of defence force personnel. Refer to table A6 page 56 of the appendix to view the data pertaining to these graphs. 42 Babies Health service use Average duration of stay in hospital Royal Darwin Hospital 0 1 2 3 4 5 6 7 1985 1987 1989 1991 1993 1995 Days Aboriginal Non-Aboriginal Darwin Private Hospital 0 1 2 3 4 5 6 7 1985 1987 1989 1991 1993 1995 Days Gove District Hospital 0 1 2 3 4 5 6 7 1985 1987 1989 1991 1993 1995 Days Katherine Hospital 0 1 2 3 4 5 6 7 1985 1987 1989 1991 1993 1995 Days Tennant Creek Hospital 0 1 2 3 4 5 6 7 1985 1987 1989 1991 1993 1995 Days Alice Springs Hospital 0 1 2 3 4 5 6 7 1985 1987 1989 1991 1993 1995 Days • The average length of stay for both Aboriginal and non-Aboriginal babies decreased throughout the decade, with Aboriginal babies staying in hospital longer than non-Aboriginal babies. • The geometric mean was used for summary data and comparisons here because the distribution of length of stay data approximates the log normal distribution. . Refer to table A7 page 57 of the appendix to view the data pertaining to these graphs. 43 Babies Mortality Foetal deaths No of stillbirths per 1,000 total births 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 5 10 15 20 25 30 Aboriginal Non-Aboriginal Table 32: Number of stillbirths per thousand total births, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Aboriginal 27.5 28.1 26.2 29.3 21.9 18.1 18.0 20.0 14.8 16.8 Non-Aboriginal 5.2 8.1 9.0 5.4 12.6 8.9 8.9 6.5 8.3 6.7 Total 12.7 15.3 14.7 13.8 15.7 12.0 12.0 11.3 10.5 10.1 • A stillbirth or a foetal death is usually defined as the absence of any evidence of life after the foetus has been separated from its mother. Only foetuses who had reached at least 20 completed weeks gestation or 400 grams at delivery are included as a stillbirth for the purposes of this report. • The stillbirth rate is calculated as the ratio of the number of stillbirths to total births, where the number of total births is obtained as the sum of stillbirths plus livebirths. • There has been a steady decline in the overall Northern Territory stillbirth rate from 12.7 deaths per thousand total births in 1986 to 10.1 in 1995. • Much of this decline can be attributed to improvements in Aboriginal stillbirth rate which declined by about 40% from 27.5 stillbirths per thousand total births in 1986 to 16.8 in 1995. • Although the non-Aboriginal stillbirth rate has been subject to substantial fluctuations between 1986 and 1995, there is no evidence of any 44 Babies Mortality Neonatal deaths No of deaths per 1,000 livebirths 10 15 20 Aboriginal 5 Non-Aboriginal 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 33: Number of neonatal deaths per thousand livebirths, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Aboriginal 22.1 17.5 18.5 16.4 22.4 14.3 12.5 17.2 19.7 9.8 Non-Aboriginal 5.2 3.9 5.9 5.5 6.1 6.8 6.4 4.4 4.0 5.0 Total 10.8 8.7 10.1 9.2 11.6 9.3 8.4 8.8 9.5 6.6 • Neonatal mortality is defined as the death of a liveborn infant who dies before 28 completed days of life. The risk of early neonatal mortality (particularly in the first week of life) is a good indicator of the adequacy of perinatal care. • The neonatal mortality rate is expressed as the number of neonatal deaths per thousand livebirths. • There has been a steady decline in the overall Northern Territory neonatal mortality rate from 10.8 deaths per thousand live births in 1986 to 6.6 in 1995. • Much of this decline can be attributed to improvements in the Aboriginal rate which declined by more than half from 22.1 deaths per thousand livebirths in 1986 to 9.8 in 1995. • The non-Aboriginal neonatal mortality rate has remained relatively stable during the study period. In 1986, the rate was 5.2 deaths per thousand livebirths compared with 5.0 in 1995. 45 Babies Mortality Perinatal deaths No of perinatal deaths per 1,000 total births 25 30 35 40 45 50 Aboriginal 10 15 20 Non-Aboriginal 5 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Table 34: Number of perinatal deaths per thousand total births, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Aboriginal 48.9 45.1 44.2 45.2 43.8 32.2 29.3 36.9 34.0 26.4 Non-Aboriginal 10.4 12.0 14.9 10.9 18.6 15.6 15.1 10.9 12.2 11.6 Total 23.3 23.9 24.6 22.9 27.2 21.2 20.0 20.0 19.8 16.7 • Perinatal deaths include the number of stillbirths • There has been a steady decline in the overall and neonatal deaths that occur in any one Northern Territory perinatal mortality rate from calendar year. 23.3 deaths per thousand total births in 1986 to 16.7 in 1995. • The perinatal mortality rate is expressed as the number of perinatal deaths per thousand total • Much of this decline can be attributed to births. This measure is usually considered to be improvements in the Aboriginal rate which a reflection of standards of obstetric and declined by about 45% from 48.9 deaths per paediatric care as well as the effectiveness of thousand livebirths in 1986 to 26.4 in 1995. social measures in general and of specific public health actions. • The non-Aboriginal neonatal mortality rate has remained relatively stable during the study period. In 1986, the rate was 10.4 deaths per thousand livebirths compared with 11.6 in 1995. 46 Babies Mortality Infant deaths No of infant deaths per 1,000 livebirths 50 45 40 20 25 30 35 Aboriginal 15 Non-Aboriginal 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 5 10 Table 35: Infant mortality rate: No. of infant deaths per thousand livebirths, NT, 1986–95 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Aboriginal 36.2 31.6 28.7 29.3 32.7 26.9 31.5 30.3 24.7 18.7 Non-Aboriginal 8.3 6.3 8.2 8.2 8.8 8.5 7.6 5.2 4.8 7.1 Total 17.5 15.2 14.9 15.5 16.9 14.7 15.8 14.0 11.7 11.0 • The infant mortality rate is measured as the number of infant deaths per thousand livebirths in any one year. This rate has long been a good indicator of hygiene and health conditions prevailing in a population. • The infant mortality rate is composed of the rates prevailing in two time periods of an infant's life: the neonatal period (the first four weeks of life) and the postneonatal period (4–51 weeks of life). The neonatal period mostly reflects the effectiveness of health services and the postneonatal period reflects social conditions. • There has been a steady decline in the Northern Territory infant mortality rate from 17.5 deaths per 1,000 livebirths in 1986 to 11.0 in 1995. • Much of the decline can be attributed to improvements in the Aboriginal rate which declined by about 50% from 36.2 deaths per thousand livebirths in 1986 to 18.7 in 1995. • The non-Aboriginal neonatal mortality rate has remained relatively stable during the study period. In 1986, the rate was 8.3 deaths per thousand livebirths compared with 7.1 in 1995. 47 Appendix Definitions Explanatory notes Additional data tables • Antenatal care in the first trimester of pregnancy by district (mothers) – page 13 • Induction of labour by hospital (mothers) – page 23 • Caesarean section by hospital (mothers) – page 25 • Average duration of postnatal stay by hospital (mothers) – page 31 • Average birthweight by district (babies) – page 39 • Hospital of birth (babies) – page 42 • Average duration of stay in hospital (babies) – page 43 48 Appendix Definitions In Australia, the reporting of perinatal and infant mortality rates varies from State to State. Nationally agreed reporting standards have not yet been accepted. It should be noted that some of the definitions below differ from those used by the Australian Bureau of Statistics (ABS) which follows those recommended (for national reporting) by the World Health Organisation (WHO). These define stillbirth as a stillborn infant weighing at least 500g or, if the weight is not known, born after at least 22 weeks gestation. The WHO has further definitions of live births and stillbirths for the reporting of statistics for international comparisons, namely those infants weighing 1,000 grams or if the weight is not known, 28 weeks gestation. In addition, WHO recommends that only neonatal deaths occurring in the first seven days of life should be reported and not all deaths up to 28 days. Convention also differs with the reporting of infant deaths. The ABS records deaths as occurring in the year in which they are registered (with each states Registrar of Births, Deaths and Marriages), while some states record the death with the statistics of the year in which the baby was born. Even though there are advantages with each of these methods, the NT (and some other states) includes infant deaths in the statistics of the year in which they occurred (see definitions below). The National Perinatal Statistics Unit (NPSU), which is responsible for national reporting, obtains its data from the ABS and therefore will report different statistics from those in this report. The ABS publication on Northern Territory demography will also differ. Aboriginal: A person of Aboriginal or Torres Strait Islander descent who identifies as an Aboriginal or Torres Strait Islander and is accepted as such by the community with which he or she is associated. Apgar score: A numerical scoring system routinely administered at one and five minutes after birth to evaluate the condition of the baby. The score ranges from 0 to 10 (10 being optimal condition). It takes account of five physical signs: heart rate, respiration, muscle tone, reflexes and colour, each of which is assigned a component score of 0, 1 or 2. Birthweight: The first weight of the foetus or baby obtained after birth. Extremely low birthweight: less than 1,000g. Very low birthweight: less than 1,500g. Low birthweight: less than 2,500grams. 49 Appendix Definitions Caesarean section: Delivery of the baby through an abdominal incision. Elective caesarean section: A caesarean section (planned or unplanned) performed before the onset of labour. Emergency caesarean section: A caesarean section performed after the onset of labour, whether or not the onset of labour was spontaneous. Caesarean section rate: The number of caesarean sections divided by the total number of births. Confinement: A pregnancy resulting in at least one birth. Note: with a multiple pregnancy, one confinement will result in more than one birth. District of usual residence: The district within the NT in which the mother usually resides. See Map on page(viii). Gestation age: The duration of pregnancy in completed weeks from the first day of the last normal menstrual period. Gestation age is estimated from clinical assessment (including ultrasound) when accurate information on the last menstrual period is not available. Gravidity: The number of previous pregnancies. Induction of labour: Includes both medical and surgical induction of labour, where labour was initiated by the use of drugs such as oxytocic agents, prostaglandins, or their derivatives (medical induction), or where labour was initiated by artificial rupture of membranes (surgical induction). 50 Appendix Definitions Infant death: The death of a live born infant occurring within the first year of life. Infant mortality rate: The number of infant deaths in a year per 1,000 live births in the same year. Instrumental delivery: Vaginal delivery by forceps or Ventouse. Live birth: The complete expulsion or extraction from its mother of a baby, irrespective of duration of pregnancy, which after separation shows some signs of life. Note that in contrast with stillbirths, there is no lower limit of gestational age or birthweight. Neonatal death: The death of a liveborn infant within 28 days of birth. Neonatal mortality rate: The number of neonatal deaths in a year per 1,000 live births in the same year. Parity: The total number of live births and stillbirths of at least 20 weeks gestation before the mother's current pregnancy or birth under consideration. Perinatal death: A stillbirth or neonatal death. Plurality: The number of births resulting from a pregnancy. Premature infant: An infant born before 37 completed weeks gestation. Post-neonatal death: The death of a liveborn infant occurring after the first 28 days and within the first year of life. 51 Appendix Definitions Perinatal mortality rate: The number of stillbirths and neonatal deaths in a year per 1,000 total births in the same year. Stillbirth: The complete expulsion or extraction from its mother of a baby of at least 20 weeks gestation, or 400g birthweight, which, after separation, did not breathe or show any sign of life. Also referred to as late foetal death. Stillbirth rate: The number of stillbirths in a year per 1,000 total births in the same year. Total fertility rate: The number of children a woman would have, if throughout her reproductive years, she had children at the age-specific rates that were observed in any one year. 52 Appendix Explanatory notes Health districts The provision of health services in the Northern Territory is planned and administered by Territory Health Services through seven health district (see map on page viii of the preface). The seven health districts include the Top End districts of Darwin Urban, Darwin Rural, East Arnhem and Katherine and the Central Australian districts of Alice Springs Urban, Alice Springs Rural and Barkly. Hospital There are six hospitals in the Northern Territory – three relatively large hospitals and three relatively small regional hospitals. The major hospitals include the Royal Darwin Hospital, the Darwin Private Hospital and the Alice Springs Hospital. The three regional hospitals are Gove District Hospital (East Arnhem district), Katherine Hospital (Katherine district) and Tennant Creek Hospital (Barkly district). Medical conditions and complications There were five groups of conditions on the Midwives’ collection form which related to complications or illnesses in mother or infant. Until 1996, these conditions were not strictly defined, rather the condition was deemed to be present if the diagnosis was made and documented in the hospital or antenatal record and noted by the midwife. From 1996, some, but not all, of these conditions are defined in the “NT Midwives Collection data reporting guidelines”. It should be noted that mothers and babies may have more than one of these conditions. Test of statistical significance: Tests of statistical significance in 2 by 2 tables have used chi-squared methods. Analysis of variance and t-tests have been used to test for significant differences between means. The cut-off for statistical significance is p<0.05. The relatively small numbers of observations in the NT Midwives datasets means that at times the various estimates can be unstable. Care must be exercised when interpreting the results presented in this report. 53 ........ AppendixAppendixAppendixAppendixAppendix.... DataDataDataDataData Table A1: Percentage distribution of mothers who received antenatal care in the first trimester of their pregnancy by district, NT, 1986–95 Alice Alice Darwin Darwin East Springs Springs Year Urban Rural Arnhem Katherine Barkly Urban Rural Aboriginal 1986 25.4 15.8 4.1 16.3 2.6 21.3 5.2 1987 17.0 18.7 6.6 15.6 10.3 22.8 4.3 1988 18.2 18.3 6.0 18.6 8.8 24.4 3.7 1989 17.3 15.8 12.6 20.5 10.7 20.5 7.4 1990 25.6 11.0 25.0 19.5 23.2 9.9 1991 23.8 25.6 14.2 23.9 7.6 23.7 12.9 1992 19.5 29.9 16.9 32.0 26.7 29.5 15.5 1993 15.0 27.3 19.2 38.8 16.8 1994 23.4 30.1 41.0 1995 18.3 32.9 33.3 18.3 Non-Aboriginal 1986 42.9 37.7 50.7 74.1 52.7 56.8 58.3 1987 40.4 52.0 47.9 76.8 41.1 58.3 38.9 1988 35.7 45.3 54.5 78.3 64.9 57.1 1989 33.3 41.4 62.9 70.4 48.9 69.3 62.1 1990 32.5 41.6 39.0 76.1 55.4 63.0 52.4 1991 35.2 45.3 59.4 77.8 55.6 70.4 69.2 1992 47.9 70.9 73.1 85.7 1993 39.1 68.8 54.2 69.2 43.5 1994 65.8 40.0 64.8 56.5 1995 76.4 68.8 47.6 Note: The graph for these data appears on page 13. Where there was more than 10% 'Unreported', the data were considered unreliable and omitted from the table. Table A2: Percentage distribution of women who were induced by hospital, NT, 1986–95 Royal Darwin Tennant Alice Year Darwin Private Gove Katherine Creek Springs Aboriginal 1986 8.6 -9.8 19.2 0.0 13.5 1987 8.7 -21.6 6.0 4.6 14.6 1988 11.6 -12.6 13.0 4.7 10.1 1989 13.8 -3.2 11.1 2.6 12.9 1990 12.1 -8.8 6.3 2.5 12.5 1991 12.9 -8.2 4.6 2.7 14.6 1992 17.9 -9.5 9.7 0.0 18.2 1993 9.8 -19.3 9.9 12.8 19.2 1994 8.7 -8.6 9.5 5.1 23.6 1995 11.9 -0.8 14.7 2.1 20.3 Non-Aboriginal 1986 22.1 -10.3 28.9 9.5 13.5 1987 21.6 -14.3 18.0 8.7 11.9 1988 16.9 -22.5 15.4 2.5 12.0 1989 16.8 -1.4 17.6 10.3 18.8 1990 17.9 27.1 7.4 11.3 4.2 14.9 1991 20.1 32.3 12.0 12.8 7.7 18.6 1992 22.1 32.3 20.4 14.2 11.1 19.0 1993 14.5 38.2 17.6 19.5 0.0 21.7 1994 12.0 34.3 21.2 21.0 5.9 20.4 1995 18.5 35.2 8.9 20.8 0.0 18.6 Note:The graph for these data appears on page 23. 54 Appendix Data Table A3: Percentage distribution of women who delivered by caesarean section by hospital, NT, 1986–95 Royal Darwin Alice Year Darwin Private Gove Katherine Springs Aboriginal 1986 20.0 --22.6 22.2 1987 24.7 -16.5 19.0 19.3 1988 17.8 -19.7 20.8 20.9 1989 18.6 -19.0 19.0 18.6 1990 19.7 -19.8 22.2 20.7 1991 18.5 -15.6 14.4 21.0 1992 25.4 -19.8 16.6 22.2 1993 28.8 -17.6 17.7 22.5 1994 27.1 -23.1 20.7 24.8 1995 29.5 -18.5 23.9 27.7 Non-Aboriginal 1986 13.5 --22.6 16.0 1987 17.1 --19.0 13.4 1988 12.3 --20.8 16.6 1989 11.4 --19.0 15.3 1990 12.3 17.4 -22.2 19.3 1991 14.4 15.8 -14.4 15.2 1992 16.6 19.9 -16.6 16.4 1993 23.5 17.9 -17.7 17.7 1994 21.8 22.8 -20.7 13.0 1995 19.4 22.0 -23.9 14.5 Note: The graph for these data appears on page 25. Table A4: Average duration of mothers' postnatal stay by hospital (in days), NT, 1986–95 Royal Darwin Tennant Alice Year Darwin Private Gove Katherine Creek Springs Aboriginal 1986 6.5 -5.8 6.1 3.4 5.4 1987 6.6 -5.5 5.6 4.1 5.3 1988 6.0 5.5 5.6 5.3 3.9 5.3 1989 5.6 5.3 5.6 4.8 3.5 5.0 1990 5.1 5.4 6.2 5.7 3.5 4.9 1991 5.5 5.3 5.4 5.1 3.1 4.7 1992 4.6 5.4 5.9 5.4 3.1 5.1 1993 4.6 5.2 4.9 4.8 2.6 4.5 1994 4.6 -4.5 5.6 2.7 4.4 1995 4.3 -4.7 5.0 2.7 4.8 Non-Aboriginal 1986 4.6 4.5 4.0 3.7 3.6 1987 4.7 4.1 3.7 3.2 3.7 1988 4.3 5.5 4.3 3.9 3.7 3.9 1989 3.7 5.3 4.8 4.1 3.1 3.8 1990 3.7 5.4 4.4 4.1 3.8 3.7 1991 3.5 5.3 4.1 4.0 3.6 3.4 1992 3.3 5.4 4.0 3.8 2.8 3.4 1993 3.4 5.2 4.2 4.2 2.3 3.4 1994 3.4 3.3 4.4 2.6 3.4 1995 3.1 2.9 3.7 2.4 3.2 Note: The graph for these data appears on page 31. 55 Appendix Data Table A5: Average birthweight of livebirths, NT, 1986–95 Alice Alice Darwin Darwin East Springs Springs Year Urban Rural Arnhem Katherine Barkly Urban Rural Aboriginal 1986 3094 2928 2887 2965 3061 3304 3121 1987 3141 3027 2838 3066 3047 3301 3116 1988 3211 2997 2865 3052 2983 2972 3194 1989 3079 3086 2941 3144 2943 3184 3037 1990 3263 2995 2870 3015 3055 3079 3035 1991 3211 2970 2873 3112 3123 3242 3030 1992 3096 2936 2851 3128 3164 3239 3066 1993 3083 3110 2891 3118 3176 3253 3132 1994 3116 3064 2999 3150 3098 3350 3061 1995 3302 3022 2988 3124 3060 3270 3167 Non-Aboriginal 1986 3283 3388 3379 3392 3269 3325 3426 1987 3311 3284 3430 3341 3251 3397 3274 1988 3263 3364 3401 3323 3335 3365 3276 1989 3305 3268 3463 3357 3178 3413 3252 1990 3301 3456 3190 3314 3206 3326 3354 1991 3268 3372 3348 3312 3230 3346 3160 1992 3268 3264 3246 3344 3376 3348 3032 1993 3281 3349 3410 3319 3286 3390 3597 1994 3298 3281 3388 3338 3505 3363 3418 1995 3316 3333 3348 3382 3111 3484 3403 Note:The graph for these data appears on page 39. Table A6: Number of births by hospital of birth, NT, 1986–95 Royal Darwin Tennant Alice Year Darwin Private Gove Katherine Creek Springs Aboriginal 1986 397 -82 148 36 299 1987 383 -97 170 44 302 1988 360 -128 155 43 282 1989 381 -126 189 38 282 1990 412 10 91 176 40 298 1991 374 10 147 174 37 331 1992 424 16 116 176 39 355 1993 446 20 119 141 39 339 1994 431 16 117 170 39 324 1995 431 11 119 184 48 328 Non-Aboriginal 1986 1546 -39 128 21 408 1987 1344 -56 129 23 468 1988 818 -72 169 40 443 1989 824 -71 149 29 405 1990 884 576 54 179 24 454 1991 816 714 92 158 26 471 1992 936 695 54 213 9 436 1993 892 661 74 207 7 423 1994 945 670 52 168 17 423 1995 995 688 56 201 14 388 Note:The graph for these data appears on page 42. 56 Appendix Data Table A7: Average duration of stay in hospital in days by hospital, NT, 1986–95 Royal Darwin Tennant Alice Year Darwin Private Gove Katherine Creek Springs Aboriginal 1986 6.4 -5.1 5.9 3.4 5.3 1987 6.7 -5.3 5.6 4.1 5.2 1988 5.9 -5.2 5.3 4.1 5.2 1989 5.7 -5.3 4.7 3.5 5.1 1990 5.4 6.5 6.2 5.7 3.5 5.0 1991 5.8 4.8 5.5 5.1 3.1 4.6 1992 4.9 5.8 5.6 5.3 3.2 5.2 1993 4.9 5.7 4.9 4.6 2.6 4.7 1994 4.9 4.6 4.5 5.6 2.7 4.5 1995 4.7 5.0 4.9 4.8 2.6 4.8 Non-Aboriginal 1986 4.8 -4.5 4.0 3.6 3.6 1987 4.9 -4.1 3.7 3.2 3.8 1988 4.5 -4.4 3.8 3.7 3.9 1989 3.9 -4.8 4.1 3.2 3.9 1990 3.9 5.5 4.4 4.1 3.8 3.8 1991 4.0 5.4 4.1 4.0 3.5 3.5 1992 3.5 5.5 4.0 3.8 2.8 3.4 1993 3.6 5.5 4.3 4.2 2.3 3.5 1994 3.6 5.3 3.4 4.4 2.6 3.5 1995 3.4 5.4 3.0 3.7 2.4 3.3 Note: The graph for these data appears on page 43. 57 ................................ Epidemiology Branch publicationsEpidemiology Branch publicationsEpidemiology Branch publicationsEpidemiology Branch publicationsEpidemiology Branch publications Published reports Health of mothers and babies • A series of annual reports of the NT Midwives Collection have been published by the Epidemiology branch since data were first collected in 1986. Morbidity and mortality • Plant AJ, Condon JR & Durling G (1995). Northern Territory Health Outcomes – Morbidity and Mortality 1979–1991. Northern Territory Department of Health & Community Services, Darwin. This report documents Northern Territory mortality, maternal and child health and notifiable communicable diseases for the period 1979–91 and hospital separations for the period 1979–88 (excluding 1981). Diabetes • Markey P, Weeramanthri T & Guthridge S (1996). Diabetes in the Northern Territory. Diabetes Australia, NT, Darwin. This report was an initiative of Diabetes Australia Northern Territory branch and was produced as a collaborative effort between Diabetes Australia NT and the Epidemiology Branch. Copies of the report are only available from Diabetes Australia. Cancer • d'Espaignet ET, Measey ML, Condon JR, Jelfs P & Dempsey KE (1996). Cancer in the Northern Territory 1987–1993. Territory Health Services, Darwin This report provides information on the incidence and mortality associated with cancers but excludes data on malignant non-melanocytic skin cancer. The information is presented by sex for Aboriginal and non-Aboriginal residents of the Northern Territory for the period 1987–93 as well as for the total Australian population for the period 1987–90. Forthcoming reports (with expected release date in bracket) Demography of the NT seven health districts: A presentation of population size by age, sex and Indigenous Status for the seven health districts of the Northern Territory (March 1998). Mortality and morbidity attributable to smoking in the Northern Territory: An analysis of deaths and hospital admissions due to smoking in the Top End and Central regions of the Northern Territory (March 1998) Hospital morbidity in the Northern Territory: An analysis of of hospital admissions by age, sex, Indigenous status and reason for admission for the period 1993–97 (April 1998) Mortality in the Northern Territory: An analysis of mortality by age, sex and cause of death for the seven health districts for the period 1979–96 (May 1998) Cancer in the Northern Territory: An analysis of incidence and mortality from cancer in the Northern Territory for the period 1987–96 (second half 1998) 58