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