The purpose of this study was to compare perinatal and neonatal outcomes in triplet gestations based on placental chorionicity. We hypothesized that triplets containing a monochorionic twin pair (dichorionic-triamniotic) would have increased morbidity/mortality compared with triplets without a monochorionic twin pair (trichorionic).METHODS:
This was a retrospective cohort study of triplet gestations delivered at greater than 20 weeks at our institution from 2009–2015. Data was abstracted through electronic medical records. The primary outcome was composite neonatal morbidity/mortality; respiratory distress syndrome, intraventricular hemorrhage, necrotizing enterocolitis, under 10th percentile birth weight, death.RESULTS:
42 sets of triplets were included; 26 trichorionic-triamniotic, 14 dichorionic-triamniotic, and 2 monochorionic-triamniotic. The dichorionic and monochorionic gestations were combined into one group (n=16) for the comparisons. Maternal baseline characteristics were comparable. There were no significant differences in pregnancy complications including the presence of a shortened cervix, cerclage placement, use of tocolytics, premature rupture of membranes, pregnancy-induced hypertension, gestational diabetes, or twin-twin transfusion syndrome. Increased risk of intrauterine growth restriction was noted in the dichorionic and monochorionic group compared to the trichorionic group (25% vs 3.8%), however, the difference was not statistically significant due to the small number of patients (P=.06). There was a significant difference in the composite morbidity/mortality between the groups. All dichorionic and monochorionic gestations suffered some morbidity.CONCLUSION:
Dichorionic triplet gestations are at an increased risk of neonatal morbidity/mortality when compared to trichorionic triplet gestations. Further research is needed to elucidate the risk factors that increase the risk of monozygotic twinning.