A trial of labor after caesarean section with a macrosomic neonate. Is it safe?

Abstract Objective: To determine whether a trial of labour after caesarean section (TOLAC) with a macrosomic neonate is associated with adverse outcomes. Methods A retrospective cohort study was conducted in a population motivated for TOLAC.Women attempting TOLAC with a neonatal birthweight >4000g were compared to women attempting TOLAC with neonatal birthweights between 3500g-4000g. The primary outcome was TOLAC success. Secondary outcomes included mode of delivery, uterine rupture, postpartum haemorrhage (PPH), shoulder dystocia, obstetric anal sphincter injury (OASI), Apgar <7 at 5 min and umbilical artery pH <7.1). Data were analysed using Fisher's exact test and chi‐square tests.Results: 375 women who underwent TOLAC with a neonate weighing >4000 g comprised the study group. 1783 women attempting TOLAC with a neonate weighing 3500-4000g comprised the control group. There were no clinically significant differences between the groups for maternal age, gestational age, parity and VBAC rate. There were no significant differences in the rates of successful TOLAC (94% versus 92.3%, P = 0.2, OR = 0.8, 95% CI 0.5–1.2), operative vaginal delivery (7.4% versus 5.3%, P = 0.18, OR 0.7, 95% CI 0.4–1.1), uterine rupture (0.4% versus 0% P = 0.6), PPH (3.2% Vs 2.3 % p=0.36 OR 1.4 CI 0.7,2.7) , OASI (0.8% Vs 0.2% p=0.1 OR 3.6 CI 0.8,1.6), Apgar <7 at 5 mins (0% Vs 0.4% p=0.37) and umbilical artery pH 4000 g had a significantly increased risk of shoulder dystocia (4% Vs 0.4% p <0.05, OR 9.2 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 helps counsel women considering TOLAC with a macrosomic fetus.