Achievement of Body Mass Index Specific Weight Gain Recommendations: Impact on Preterm Birth in Twin Pregnancies

Objective To determine whether achievement of body mass index specific weight gain recommendations is associated with reduced preterm birth or neonatal morbidity among twin gestations. Study Design This was a retrospective cohort study of twin gestations delivered at the Medical University of South Carolina from 2000 to 2010. In total, 588 women in all prepregnancy body mass index categories who delivered ≥24 weeks' gestation were included. Women were grouped as achieved or underachieved based on total weight gain and gestational age at delivery. Maternal and neonatal outcomes were compared between the groups. Results Body mass index specific weight gain goals were achieved by 59.9% of women. The achieved group had a 1.5-fold reduction in the rate of preterm birth <32 weeks (18.8 vs. 30.5%; p = 0.001). Achievers had larger mean birthweights (2,146 ± 584 g vs. 1,859 ± 593 g; p < 0.001) and were significantly less likely to deliver either twin with a birthweight less than the 10th percentile for gestational age (larger twin 0.6 vs. 4.7%, p = 0.001; smaller twin 12.2 vs. 21.6%, p = 0.002). Composite neonatal morbidity, days on the respirator, length of hospital stay, and rate of neonatal intensive care unit admission were significantly decreased in the achieved group. Conclusion Achievement of body mass index specific weight gain goals improves preterm birth rates, neonatal birthweights, and composite neonatal outcomes in women carrying twins.