Is South Asian ethnicity a risk factor for adverse outcomes in the post-term period? [BJOG]

Abstract

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, with the relative risk increasing progressively with gestation. The underlying mechanisms remain unclear but may involve 'accelerated placental ageing'. Whether the risk of other perinatal complications increases earlier in Asian women is not known. Our aim was to determine if post-term South Asian-born women were more likely to demonstrate abnormalities suggesting fetal compromise in later pregnancy compared to Australian-born women. Methods A retrospective cohort of singleton births in nulliparous women from 2009 to 2011 at >=10 days post-term (41 weeks and 3 days gestational age) with available surveillance records was conducted. A total of 145 South Asian-born (SA) and 272 Australian-born were studied. Differences in amniotic fluid index (AFI), CTG, intrapartum fetal compromise, mode of delivery and perinatal outcomes were compared between the two groups. The relationship between maternal ethnicity, intrapartum fetal compromise and emergency caesarean delivery was assessed by logistic regression, adjusting for potential confounders. Results SA women were more likely to have an abnormal CTG (10.3% versus 3.3%, P = 0.004), but not a significantly lower AFI (14.5% versus 9.9%, P = 0.11) compared with Australian born women. Consequently SA women were more likely to undergo an induction of labour (70.3% versus 59.2%, P = 0.020), and after adjustment for confounders, SA women were 65% more likely to have an emergency caesarean (95% CI 1.07-2.53, P = 0.02). SA women were also more likely to demonstrate intrapartum fetal compromise (55.9% versus 44.5%, P = 0.017), however this association did not persist after adjusting for confounders. There was a higher rate of Special Care Nursery or Neonatal Intensive Care Unit admission in babies born to SA women(28.5% versus 20.6%, P = 0.047), but no significant difference in Apgar scores or cord lactates. Conclusion These findings suggest that SA women are at higher risk of markers of fetal compromise post-term. This supports the hypothesis that risk of perinatal complications may increase earlier in SA women than in Caucasian women as a result of 'accelerated placental ageing'. Given the increasing proportion of overseasborn 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.