There is no significant increase in the risk of severe PPH with trial of labor among women with low-lying placenta after 35 weeks of gestation and an internal os distance of 11-20 mm compared to cesarean births, suggests a recent study from France reported in the journal Obstetrics and Gynecology.¹ The maternal and neonatal morbidity rates were was also similar between the two groups.

A retrospective multicenter study analysed data for 128,233 births that took place between 2007 and 2012. Women with low-lying placenta who delivered after 35 weeks of gestation at six tertiary maternity hospitals in France were selected for the study. The selected participants were categorized into planned trial-of-labor group or elective cesarean delivery group to study the outcomes with regard to the mode of delivery. An internal os distance of ≤20 mm was considered as low-lying placenta.

Seventy (~41%) women in the trial of labor group had low-lying placenta, while in the elective cesarean delivery group, 101 women (59.1%) had low lying placenta. Among women who were given a trial of labor, severe PPH (blood loss ≥1000 ml), which was the primary outcome, occurred in 22.9% (16/70) women. The PPH rate was 23% (23/101) among women in the cesarean section group. The two groups had likewise comparable maternal (2.9% vs 2.0%) and neonatal (12.9% vs 9.9%) morbidity rates. In the trial of labor group, half of the women with (19/38) an internal os distance of 11-20 mm delivered vaginally, whereas only 5 out of the 27 women (27.5%) with internal os distance of 1-10 mm had vaginal births.

Based on these findings, the study authors recommend that these women can be given a trial of labor before proceeding to an elective cesarean birth.

Reference

1. Alizée Froeliger  et al. Trial of labor compared with elective cesarean delivery for low-lying placenta. Obstet Gynecol. 2022 Aug 3. doi: 10.1097/AOG.0000000000004890.