The risk of adverse maternal outcomes in cases of placenta praevia in an Australian population between 2007 and 2017

Background: Placenta praevia is characterised by an inferior placental margin that overlies or falls within 20 mm of the endocervical os. It remains a common cause of antepartum haemorrhage and is associated with adverse maternal and neonatal outcomes.

Aims: We aimed to determine the association between antepartum and postpartum haemorrhage and adverse outcomes in cases of placenta praevia.

Materials and methods: The study population included women diagnosed with placenta praevia, who delivered between 1 April 2007 and 30 April 2017. The endpoints of interest included blood transfusion, emergency caesarean section, peripartum hysterectomy and admission to intensive care.

Results: There were 513 cases of placenta praevia, of which 67.3% delivered at term. Antepartum haemorrhage was associated with an increased risk of blood transfusion (relative risk (RR) 3.29; 95% CI 2.04-5.32), emergency caesarean section (RR 1.38; 95% CI 1.18-1.62) and preterm delivery, after 32 weeks gestation (RR 4.21; 95% CI 2.77-6.38). Postpartum haemorrhage more than doubled the risk of blood transfusion (RR 9.08 95% CI 5-16.44) and admission to the intensive care unit (RR 10.44; 95% CI 2.34-46.59), as well as increased the risk of peripartum hysterectomy (1.4%). We also described the management of 12 cases of placenta praevia (2.3% of the study population) delivered vaginally.

Conclusions: Antepartum and postpartum haemorrhage in cases of placenta praevia are predictors of several adverse outcomes. However, the high rate of term deliveries reaffirms the current practice of expectant management.