Higher risk of hemorrhage and maternal morbidity in vaginal birth after second stage of labor C-section.

Purpose: This study evaluated the association between timing and indication for previous cesarean section (C-section) and its association with postpartum risks for adverse maternal outcomes, primarily postpartum hemorrhage (PPH) in vaginal birth after cesarean (VBAC).

Methods: This retrospective case-control study examined women following term vaginal delivery in a university-affiliated medical center between 2008 and 2018. Postpartum complications were compared between women who had their first VBAC and a control group comprised of women who had vaginal delivery without prior C-section. Additional analysis was performed to evaluate the association between the timing of previous C-section and the severity of postpartum adverse outcomes.

Results: Of the women meeting the inclusion criteria (n = 2879), 1,455 had VBAC and 1,424 were in the control group. Overall, significant postpartum complications, primarily PPH, were observed in the VBAC group compared to controls. Women who underwent C-section during second-stage of labor experienced higher PPH rates and increased drop in hemoglobin levels compared to women who underwent C-section during the first stage of labor or an elective C-Sect. (4.3 ± 0.9 g/dL vs. 2.8 ± 1.1 g/dL vs. 2.4 ± 0.8, p = 0.033). Concomitant increased need for blood transfusion (8.1% vs. 3.5% vs. 2.9%, respectively, p < 0.0001) and uterine atony (12.6% vs. 6.2% vs. 4.4%, respectively, p = 0.009) were also observed. No significant differences were demonstrated in other postpartum adverse effects evaluated.

Conclusion: VBAC is associated with higher rates of postpartum complications, primarily PPH. The risk is significantly increased in VBAC following a second stage cesarean section. This data should be taken into consideration in the management of laboring women after C-section.