Outcomes of Spontaneous Labor in Women Undergoing Trial of Labor after Cesarean as Compared with Nulliparous Women: A Retrospective Cohort Study.

Objective: The objective of this study was to compare spontaneous labor outcomes in women undergoing trial of labor after cesarean (TOLAC) and nulliparas to better counsel women.
Study Design: A 4-year retrospective cohort. We included women at term in spontaneous labor with vertex singletons and no more than one prior cesarean delivery. In planned secondary analysis, we focused on a subset of women with a prior cesarean and a predicted likelihood of a successful vaginal delivery of 70% or more based on the Maternal-Fetal Medicine Units-vaginal birth after cesarean (VBAC) calculator.
Results: Our cohort included 606 TOLACS and 606 nulliparas. Women undergoing TOLAC were more likely to undergo cesarean delivery (25.7 vs. 14.7%; p  < 0.001). Severe maternal hemorrhage (1.5 vs. 0.2%; p  = 0.02) and uterine rupture (1.9 vs. 0.0%; p  < 0.01) were more likely in the TOLAC group. For the subset of women with a predicted likelihood of VBAC of 70% or more, there were no differences in cesarean delivery (16.7 vs. 14.7%; p  = 0.51), maternal, or immediate neonatal complications.
Conclusion: Women undergoing TOLAC were more likely to have a cesarean delivery, hemorrhage, or uterine rupture. Those with more than 70% predicted likelihood of VBAC were no more likely to experience these outcomes. These findings help contextualize the risks of TOLAC for women considering this option.
Competing Interests: None.
(Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)