Maternal and Neonatal Outcomes of Trial of Labor Compared With Elective Cesarean Delivery According to Predicted Likelihood of Vaginal Delivery

In 2007, the Maternal-Fetal Medicine Unit (MFMU) Network developed the vaginal birth after cesarean (VBAC) calculator to help optimize the likelihood of a successful vaginal delivery. One study found that the risk of maternal and neonatal morbidity is no greater than that of elective repeat cesarean delivery (CD)-specifically when the likelihood of successful VBAC is >70%. However, the inverse has also been found. Whether the calculator accurately predicts maternal and neonatal morbidity in women undergoing trial of labor after cesarean (TOLAC) versus repeat CD is unclear. The aim of this study was to compare the risk of adversematernal and neonatal outcomes of TOLAC and elective repeat CD, stratified by predicted likelihood of VBAC success. This was a retrospective cohort study using the medical records of women whose primary CD and subsequent delivery occurred at a single hospital center between January 2009 and June 2018. Only the second delivery was analyzed. Excluded were women with multiple gestation, preterm birth, malpresentation, placental and fetal abnormalities, stillbirth, history of classic CD, active herpes simplex virus infection, and uncontrolled HIV. Using the MFMU VBAC calculator, women were stratified into 2 groups: those with VBAC likelihood of <60% and those with VBAC likelihood of 60% to 100%. The maternal outcomes were chorioamnionitis and a composite of estimated blood loss >= 1500 mL, blood transfusion, endometritis, wound infection or complication, hysterectomy, and admission to the intensive care unit. The neonatal outcomes were admission to the neonatal intensive care unit and a composite of any neonatal death, need for respiratory support, 5-minute Apgar score <4, hypoxic ischemic encephalopathy, seizure, infection, meconium aspiration, and hypotension. A total of 835 were included in the analysis: 619 (74.1%) with VBAC likelihood of 60% to 100% and 216 (25.9%) with VBAC likelihood of <60%. Of those with higher likelihood of VBAC success, 45.6% underwent TOLAC, and 54.4% chose elective repeat CD. In this group, the odds for the maternal composite outcome were lower in the TOLAC group versus the repeat CD group (adjusted odds ratio, 0.47; 95% confidence interval, 0.25-0.89). Specifically, the TOLAC group was less likely to have the maternal composite outcome (6.4% vs 11%, respectively; P < 0.05) and wound infection or complication (0% vs 3.9%; P = 0.001), but they weremore likely to have endometritis (1.4% vs 0%; P = 0.03) and chorioamnionitis (5% vs 0%; P < 0.001). There were no statistically significant differences in neonatal outcomes between the 2 groups. Among women with lower than 60% VBAC likelihood, 33.8% underwent TOLAC, and 66.2% underwent repeat CD. Women in the TOLAC group were more likely to have the maternal composite outcome (16.4% vs 4.2%, respectively; P < 0.01), estimated blood loss >= 1500 mL (6.9% vs 1.4%; P = 0.03), endometritis (5.5% vs 0%; P < 0.01), and chorioamnionitis (5.5% vs 0%; P < 0.01). Neonates in the TOLAC group were also more likely to have the neonatal composite outcome (17.8% vs 6.3%; P < 0.01) and require respiratory support (16.4% vs 6.3%; P = 0.02) and neonatal intensive care unit admission (20.6% vs 9.1%; P = 0.02). In conclusion, when the VBAC likelihood was <60%, the odds of maternal and neonatal composite outcomes increased in women who underwent TOLAC versus those who underwent elective, repeat CD. However, when the VBAC likelihood was 60% to 100%, the odds of the maternal composite were lower among women in the TOLAC group, and the odds of the neonatal composite outcome were similar. This suggests that for those predicted to have a lesser chance of successful VBAC, TOLAC may not be advisable.