Introduction: Maternal ethnicity is an emerging risk factor for adverse perinatal outcomes. South Asian women in particular are 2.4 times more likely to have a late-pregnancy antepartum stillbirth than Australian-born women[1]. This may be related to inherent differences in gestation lengths between ethnicities, the underlying mechanisms of which remain unclear[2]. Our aim was to determine if otherwise healthy post-term South Asian-born(SA) women were more likely to demonstrate fetal compromise in late pregnancy than Australian- and New Zealand-born(ANZ) women during routine post-term fetal surveillance, and whether this correlated with perinatal outcomes.
Methods: For the period 2006-2012, pregnancy outcomes for all nulliparous singleton post-term (≥41 weeks and 3 days gestation) SA and ANZ women with available post-term surveillance records at Monash Health were compared. Outcomes included abnormal post-term surveillance (AFI or CTG), onset of labour, presence of intrapartum fetal compromise, mode of delivery and neonatal outcomes.
Results: The outcomes for 145 SA and 272 ANZ women and their babies were studied. SA women were more likely than ANZ women to have an abnormal CTG (10.3% v 3.3%%, p=0.004) during post-term surveillance, but not a lower AFI (p=0.11). SA women were also more likely to undergo an induction of labour (70.3% v 59.2%, p=0.02), demonstrate intrapartum fetal compromise (55.9% v 44.5%, p=0.02) and deliver by emergency Caesarean section (51.7% v 38.2%, p=0.008). There was a higher rate of neonatal intensive care unit (NICU) admission for SA babies (28.5% v 20.6%, p=0.047), but no differences in Apgar scores or cord lactates.
Conclusion: SA women are at higher risk of maternal and neonatal morbidity in the post-term period compared to ANZ women. Given the increasing proportion of overseas-born women receiving obstetric care in Australia, the possible ethnicity-related differences in perinatal outcomes warrant further study so that tailored improvements to care can be developed.