Labor patterns in women attempting vaginal birth after cesarean with normal neonatal outcomes

Abstract

Objective: We sought to describe labor patterns in women with a trial of labor after cesarean (TOLAC) with normal neonatal outcomes.

Study design: In a retrospective observational study at 12 US centers (2002 through 2008), we examined time interval for each centimeter of cervical dilation and compared labor progression stratified by spontaneous or induced labor in 2892 multiparous women with TOLAC (second delivery) and 56,301 nulliparous women at 37 0/7 to 41 6/7 weeks of gestation. Analyses were performed including women with intrapartum cesarean delivery, and also limiting only to women who delivered vaginally.

Results: Labor was induced in 23.4% of TOLAC and 44.1% of nulliparous women (P < .001). Cesarean delivery rates were 57.7% in TOLAC vs 19.0% in nulliparous women (P < .001). Oxytocin was used in 52.4% of TOLAC vs 64.3% of nulliparous women with spontaneous labor (P < .001) and 89.8% of TOLAC vs 91.6% of nulliparous women with induced labor (P = .099); however, TOLAC had lower maximum doses of oxytocin compared to nulliparous women: median (90th percentile): 6 (18) mU/min vs 12 (28) mU/min, respectively (P < .001). Median (95th percentile) labor duration for TOLAC vs nulliparous women with spontaneous labor from 4-10 cm was 0.9 (2.2) hours longer (P = .007). For women who entered labor spontaneously and achieved vaginal delivery, labor patterns for TOLAC were similar to nulliparous women. For induced labor, labor duration for TOLAC vs nulliparous women from 4-10 cm was 1.5 (4.6) hours longer (P < .001). For women who achieved vaginal delivery, labor patterns were slower for induced TOLAC compared to nulliparous women.

Conclusion: Labor duration for TOLAC was slower compared to nulliparous labor, particularly for induced labor. By improved understanding of the rates of progress at different points in labor, this new information on labor curves in women undergoing TOLAC, particularly for induction, should help physicians when managing labor.

Keywords: first stage of labor; trial of labor after cesarean; vaginal birth after cesarean.

Figure 1. Mean labor curves for spontaneous onset of labor

Mean labor curves in singleton term pregnancies with spontaneous onset of labor, vaginal delivery, and normal neonatal outcomes for women (parity=1) with one prior cesarean and successful vaginal birth after cesarean (VBAC) and nulliparous women. Term was defined as delivery between 37 and 41 weeks of gestation. Antepartum stillbirths, women with uterine rupture, and neonates with fetal anomalies, 5 minute Apgar score < 7, sustained a birth injury or were admitted to the neonatal intensive care unit were excluded.

Figure 2. Mean labor curves for induced labor

Mean labor curves in singleton term pregnancies with induction of labor, vaginal delivery, and normal neonatal outcomes for women (parity=1) with one prior cesarean and successful vaginal birth after cesarean (VBAC) and nulliparous women. Term was defined as delivery between 37 and 41 weeks of gestation. Antepartum stillbirths, women with uterine rupture, and neonates with fetal anomalies, 5 minute Apgar score < 7, sustained a birth injury or were admitted to the neonatal intensive care unit were excluded.