A Trial of Labor after Cesarean Section with a Macrosomic Neonate. Is It Safe?

OBJECTIVE: This study aimed to determine whether a trial of labor after cesarean section (TOLAC) with a macrosomic neonate is associated with adverse outcomes. STUDY DESIGN: A retrospective cohort study was conducted in a population motivated for TOLAC. Women attempting TOLAC with a neonatal birth weight >4,000 g were compared with women attempting TOLAC with neonatal birth weights between 3,500 and 4,000 g. The primary outcome was TOLAC success. Secondary outcomes included mode of delivery, uterine rupture, postpartum hemorrhage (PPH), shoulder dystocia, obstetric anal sphincter injury (OASI), Apgar's score <7 at 5 minutes, and umbilical artery pH <7.1. Data were analyzed using Fisher's exact test and Chi-square test. RESULTS: Overall, 375 women who underwent TOLAC with a neonate weighing >4,000 g comprised the study group. One thousand seven hundred and eighty-three women attempting TOLAC with a neonate weighing 3,500 to 4,000 g comprised the control group. There were no clinically significant differences between the groups for maternal age, gestational age, parity, and vaginal birth after cesarean (VBAC) rate. There were no significant differences in the rates of successful TOLAC (94 vs. 92.3%, p = 0.2, odds ratio [OR] = 0.8, 95% confidence interval [CI]: 0.5, 1.2), operative vaginal delivery (7.4 vs. 5.3%, p = 0.18, OR = 0.7, 95% CI: 0.4, 1.1), uterine rupture (0.4 vs. 0%, p = 0.6), PPH (3.2 vs. 2.3%, p = 0.36, OR = 1.4, 95% CI: 0.7, 2.7), OASI (0.8 vs. 0.2%, p = 0.1, OR = 3.6, 95% CI: 0.8, 1.6), Apgar's score <7 at 5 minutes (0 vs. 0.4%, p = 0.37), and umbilical artery pH <7.1 (0.5 vs. 0.7%, p = 1.0, OR = 0.73, 95% CI: 0.2, 3.2). Women with a neonate weighing >4,000 g had a significantly increased risk of shoulder dystocia (4 vs. 0.4%, p < 0.05, OR = 9.2 95% CI: 3.9, 22) CONCLUSION: Women attempting TOLAC with a macrosomic neonate are not at increased risk for failed TOLAC, operative vaginal delivery, uterine rupture, PPH, or OASI but are at risk of shoulder dystocia. This information may aid in prenatal counseling for women considering TOLAC with a macrosomic fetus. KEY POINTS: · TOLAC with fetal macrosomia does not increase the risk of uterine rupture.. · TOLAC with fetal macrosomia is associated with high chances of VBAC.. · TOLAC with fetal macrosomia is not associated with adverse neonatal outcomes..