Trends in maternal and newborn health characteristics and obstetric interventions among Aboriginal and Torres Strait Islander mothers in Western Australia from 1986 to 2009.

Background: Detailed analyses of long-term trends in Aboriginal maternal and newborn health characteristics are lacking.

Aim: To examine trends in maternal and newborn health characteristics for all mothers who were recorded as Aboriginal in the Western Australian Midwives' Notification System from 1986 to 2009.

Materials And Methods: Births were categorised into four-year time intervals (1986-1989, 1990-1993, 1994-1997, 1998-2001, 2002-2005, 2006-2009). Trends in maternal demographic characteristics, pre-existing medical conditions, pregnancy complications and neonatal characteristics were examined.

Results: For 37 424 births recorded from 1986 to 2009, the proportion of births to mothers aged ≤19 years decreased (31-22%, P < 0.001) along with the prevalence of pre-eclampsia (6.8-4.0%, P < 0.001) and antepartum haemorrhage (4.8-3.2%, P < 0.001). There were increases in the prevalence of diabetes in pregnancy (3.8-6.6%, P < 0.001), induction of labour (17.8-21.4%, P < 0.001), elective caesarean (6.6-8.2%, P < 0.001) and emergency caesarean (9.5-14.9%, P < 0.001) deliveries. There were no changes in the overall prevalence of preterm births (15.4-15.9%, P = 0.32). However, increases were observed in the prevalence of medically indicated preterm births with and without prelabour rupture of membranes (1.0-1.7%; P < 0.001 and 3.3-4.3%; P = 0.005, respectively). There were no significant changes in the rates of smoking during pregnancy (51-52% from 1998 to 2009, P = 0.18), small-for-gestational age (16.9-17.2%, P = 0.07), suboptimal-birthweight (20.4-20.1%, P = 0.92), stillbirths (14.7 per 1000-12.1 per 1000, P = 0.22) and neonatal deaths (6.2 per 1000-5.5 per 1000, P = 0.68).

Conclusion: Encouraging trends include reduced rates of teenage pregnancy, pre-eclampsia and antepartum haemorrhage. The persistent high rates of smoking during pregnancy, preterm births, stillbirths, neonatal deaths and increasing rates of diabetes in pregnancy are of concern.