Nonreassuring fetal status during trial of labor after cesarean

Concern for uterine rupture has led to the decline in vaginal births after cesarean. Nonreassuring fetal status (NRFS) may precede uterine rupture. The objective of this study was to estimate the risks of uterine rupture, uterine dehiscence, and adverse fetal outcomes associated with NRFS during trial of labor after cesarean (TOLAC).

In a retrospective cohort study of the previously reported Maternal-Fetal Medicine Units Network prospective cohort cesarean registry, we compared women undergoing repeat cesarean for NRFS after TOLAC to those requiring repeat cesarean for other intrapartum indications. Exclusion criteria included women with a prior cesarean who underwent elective or indicated repeat cesarean or women with a multiple gestation. Primary outcomes included uterine rupture or dehiscence. Secondary outcomes included 5-minute Apgar score <7 and neonatal intensive care unit admission. Planned subanalyses for term and preterm deliveries were performed. Stratified and logistic regression analyses were used.

Of 17,740 women undergoing TOLAC, 4754 (26.8%) had a failed vaginal birth after cesarean. Of those, NRFS was the primary indication for cesarean in 1516 (31.9%). Women with NRFS as the primary indication for repeat cesarean were at increased risk of uterine rupture (adjusted odds ratio, 3.32; 95% confidence interval, 2.21-5.00), uterine dehiscence (adjusted odds ratio, 1.70; 95% confidence interval, 1.09-2.65), 5-minute Apgar score <7, and neonatal intensive care unit admission compared to women with other primary indications.

Women attempting TOLAC who require repeat cesarean for NRFS are at increased risk of uterine rupture and uterine dehiscence.