Objective: The purpose of this study was to calculate nationally representative, population-based estimates of maternal and neonatal risks in triplet and quadruplet pregnancies compared with twin pregnancies.
Study design: The study population included 316,696 twin, 12,193 triplet, and 778 quadruplet pregnancies from the 1995-2000 Matched Multiple Birth Data Set. Adjusted odds ratios (AORs) and 95% CIs estimated the risk of complications and were controlled for maternal age, race, parity, and smoking status.
Results: Compared with mothers of twins, mothers of triplets and quadruplets were more likely to be diagnosed with preterm premature rupture of membranes (AORs, 1.53, 1.74, respectively), pregnancy-associated hypertension (AORs, 1.22, 1.27), and excessive bleeding (AORs, 1.50, 2.22), to require tocolysis (AORs, 2.85, 5.03), and to be delivered by cesarean (AORs, 6.55, 7.38) at < 29 weeks of gestation (AORs, 3.76, 7.96), and to have > or = 1 infants die (AORs, 3.02, 4.07).
Conclusion: Triplet and quadruplet pregnancies have significantly higher risks than twin pregnancies for most maternal and neonatal complications. Maternal anthropometric, nutritional, and previous reproductive factors may be particularly important in the reduction of these excess risks and improvement of outcomes in multiple births.