Maternal and perinatal consequences of antepartum haemorrhage of unknown origin

To explore the risk of adverse maternal and perinatal outcomes in women with antepartum bleeding of unknown origin (ABUO).

Cohort study based on data extracted from the Aberdeen Maternity and Neonatal Databank. Exposure was antepartum haemorrhage occurring after the first trimester not attributable to placenta praevia or placental abruption.

Aberdeen Maternity Hospital, Aberdeen, Scotland, UK.

All primigravidae delivering between 1976 and 2010.

Data were analysed using univariate and multivariate statistical methods.

Pre-eclampsia, induced labour, mode of delivery, preterm delivery, postpartum haemorrhage, admission to neonatal unit, perinatal death.

Between 1976 and 2010, there were 7517 women with ABUO and 68,423 women without ABUO in the cohort. Women with ABUO were more likely to be non-smokers, belong to a lower social class, and have a higher body mass index. ABUO was a significant risk factor for induced labour (adjusted odds ratio, aOR, 1.23; 95% CI 1.16-1.31), preterm delivery at <37 weeks of gestation (aOR 2.30; 95% CI 2.11-2.50), and postpartum haemorrhage (aOR 1.15; 95% CI 1.06-1.25). There was no significant association detected with pre-eclampsia (aOR 0.93; 95% CI 0.83-1.05). Whereas there was an increased risk of low birthweight (aOR 0.90; 95% CI 0.79-1.03) and stillbirth (aOR 0.92; 95% CI 0.66-1.30) with ABUO on univariate analysis, once adjusted for confounding factors this risk was non-significant.

Pregnancies complicated by ABUO are at a greater risk of preterm delivery and induced labour. There was no increase seen in perinatal mortality after adjusting for preterm birth.