Maternal and neonatal outcomes of attempted vaginal compared with planned cesarean delivery in triplet gestations

The prevailing obstetric practice of planned cesarean delivery for triplet gestations is largely empiric and data on the optimal route of delivery are limited.

The primary objectives of this study are to determine the likelihood of success in an attempted vaginal delivery and assess maternal and neonatal outcomes of attempted vaginal vs planned cesarean delivery of triplets using a multiinstitution obstetric cohort.

We performed a retrospective cohort study using data from the Consortium on Safe Labor, identifying triplet pregnancies with delivery at a gestational age ≥28 weeks. Women with a history of cesarean delivery and pregnancies complicated by chromosomal or congenital anomalies, twin-twin transfusion syndrome, or a fetal demise were excluded. The attempted vaginal group included all women with spontaneous or induced labor and excluded all women delivering by prelabor cesarean delivery, including those coded as elective or for fetal malpresentation. Primary maternal outcomes included infection (composite of chorioamnionitis, endometritis, wound separation, and wound infection), blood transfusion, or transfer to the intensive care unit. Primary neonatal outcomes included neonatal asphyxia, mechanical ventilation, and composite neonatal morbidity, consisting of ≥1 of the following: birth injury, 5-minute Apgar <4, arterial pH <7.0 or base excess <-12.0, neonatal asphyxia, or neonatal death. For neonatal outcomes, Poisson regression was performed with clustering to account for correlation between neonates within a triplet pregnancy, controlling for confounders as outcome rates allowed. A sensitivity analysis was performed in the subcohort delivering at gestational age ≥34 weeks in which the attempted vaginal delivery group was restricted to include only women with evidence of induction or augmentation or labor.

188 triplet sets were identified of which 80 sets (240 neonates) met inclusion criteria and 24 sets (30%) had an attempted vaginal delivery. The rate of successful attempted vaginal delivery was 16.7% (4 triplet sets; 12 neonates). No women had a combined mode of delivery. Women attempting vaginal delivery were more likely to have preterm labor (45.8 vs 12.5%, P < .001) and receive antenatal corticosteroids (45.8 vs 21.4%, P = .03), however gestational age at delivery did not differ by mode of delivery. Attempted vaginal delivery was associated with a higher risk of maternal transfusion (20.8% vs 3.6%, P = .01) and neonatal mechanical ventilation (26.4% vs 7.7%; adjusted incidence rate ratio, 1.12; 95% confidence interval, 1.01-1.24). There was no significant difference in the risk of asphyxia or composite neonatal morbidity by mode of delivery. In the subcohort sensitivity analysis, attempted vaginal delivery was associated with an increased risk of composite neonatal morbidity (adjusted incidence rate ratio, 12.44; 95% confidence interval, 1.22-127.20) but not maternal transfusion (22.2% vs 3.5%, P = .06) or neonatal mechanical ventilation (adjusted incidence rate ratio, 1.02; 95% confidence interval, 0.89-1.17).

In a multicenter US cohort, attempted vaginal delivery of triplets is associated with higher risks of maternal transfusion and neonatal mechanical ventilation. Composite severe neonatal morbidity may be higher with attempted vaginal delivery although studies with greater power are required. The low probability of successful vaginal delivery raises questions regarding the utility of attempted vaginal delivery in triplet gestations. Our data support planned prelabor cesarean delivery as the preferred mode of delivery for triplet gestations.