Risk Factors and Associated Severe Neonatal Morbidity and Mortality at Cesarean Delivery for the Second Twin

OBJECTIVE: To evaluate the association between cesarean delivery for the second twin after vaginal delivery of the first twin and severe neonatal morbidity and mortality in comparison with vaginal delivery, and, secondarily, to identify risk factors for second twin cesarean delivery. METHODS: This was a planned secondary analysis of the JUMODA (JUmeaux MODe d'Accouchement) cohort, a national prospective population-based study of twin deliveries conducted from February 2014 to March 2015 in 176 French maternities. For this analysis, we included only second twins born after vaginal delivery of the first twin at a gestational of at least 32 weeks. The primary outcome was severe neonatal morbidity and mortality. The association of cesarean delivery for the second twin with severe neonatal morbidity and mortality in the total population was estimated from multivariate Poisson regression models. A sensitivity analysis limited to pregnancies that mirrored the Twin Birth Study low-risk population was conducted. Candidate risk factors were evaluated for cesarean delivery for the second twin. RESULTS: Among the 3,905 second twins included in analysis, 124 (3.2%) were delivered by cesarean and 3,781 (96.8%) were delivered vaginally. Cesarean delivery for the second twin was associated with severe neonatal morbidity and mortality compared with vaginal delivery (n=11/24 [8.9%] vs n=95/3,781 [2.5%]; adjusted relative risk [aRR] 3.17, 95% CI, 1.58-6.40). Findings were similar in the low-risk population (n=8/106 [7.5%] vs n=62/3,230 [1.9%]; aRR 4.03, 95% CI, 1.97-8.24). Absence of locoregional analgesia (aRR 2.13, 95% CI, 1.18-2.86), transverse second twin presentation (aRR 2.11, 95% CI, 1.44-3.08), and delivery in centers that performed fewer than 50 twin deliveries per year (aRR 1.58, 95% CI, 1.01-2.48) were associated with increased risk of cesarean delivery for the second twin. Conversely, breech second twin presentation was a protective factor (aRR 0.47, 95% CI, 0.27-0.82). CONCLUSION: In this secondary analysis of twin deliveries that involved vaginal delivery of the first twin, cesarean delivery for the second twin tripled the risk of severe neonatal morbidity and mortality when compared with vaginal delivery. Results should be interpreted with caution because of the small number of events and potential residual confounding.