Risk of postpartum hemorrhage according to the planned mode of delivery among pregnant women with one previous cesarean delivery: a secondary analysis of the Lower Uterine Segment Trial (LUSTrial).

Abstract

Background: Postpartum hemorrhage is the most common complication in obstetrics and is a leading cause of serious maternal morbidity. Women with one previous cesarean delivery are at risk for postpartum hemorrhage.

Objective: The aim of this study was to compare the risk of postpartum hemorrhage according to the planned mode of delivery among women with one previous cesarean delivery.

Study design: This study was a secondary analysis of the Lower Uterine Segment Trial. The primary outcome was postpartum hemorrhage, and the secondary outcome was a composite of severe postpartum hemorrhage including the need for blood transfusion, second-line therapy to stop bleeding, or hysterectomy. The exposure was the planned mode of delivery, which was decided at around 36 weeks of gestation. Multivariate logistic regression analysis with a random intercept of the maternity unit was used to assess the relationship between the planned mode of delivery and postpartum hemorrhage. A secondary analysis using inverse probability weighting was performed to limit indication bias.

Results: Of the 2948 women included in the Lower Uterine Segment Trial, 2889 women were included in this secondary analysis; 2689 (93.0%) chose planned vaginal delivery and 200 (7.0%) planned cesarean delivery. The rate of postpartum hemorrhage was lower in the planned cesarean delivery group than in the planned vaginal delivery group (2.5% versus 7.5%, adjusted odds ratio 0.28 [0.11-0.69] P<.01). The rate of the composite maternal outcome of severe postpartum hemorrhage was similar between the two groups (2.9% versus 2.0%, adjusted odds ratio 0.66 [0.24-1.83] P=.42). These results were consistent in the secondary analysis involving inverse probability weighting (odds ratio 0.35 [0.24-0.51] P<.01).

Conclusion: Planned cesarean delivery was associated with a lower percentage of women with postpartum hemorrhage compared with planned vaginal delivery after one previous cesarean delivery. However, the use of transfusion, second-line therapies, or hysterectomy was rare, and the rates were similar between the 2 groups.