The association of gestational weight gain per institute of medicine guidelines and prepregnancy body mass index on outcomes of twin pregnancies.

OBJECTIVE: To determine if current recommendations for weight gain in twin pregnancies according to maternal prepregnancy body mass index (PPBMI) influence perinatal outcomes. METHODS: We identified women with twins enrolled in a maternity risk screening and education program with initial screening and prenatal care initiated at <20 weeks and delivery at >23.9 weeks. Women with normal, overweight, or obese PPBMI were included (n = 5129). Pregnancy outcomes were compared between those women with weight gain meeting or exceeding 2009 Institute of Medicine recommendations and patients who did not meet weight gain guidelines. RESULTS: Rates of spontaneous preterm delivery at <35 weeks were higher in all PPBMI groups for those with weight gain below guidelines. In all PPBMI groups, numbers of pregnancies with both infants weighing >2500 g or >1500 g were significantly higher for women gaining weight at or above guidelines. Logistic regression analysis was utilized to assess multivariate impact on outcome of spontaneous preterm delivery at <35 weeks showing that regardless of PPBMI level, women who gain below recommended guidelines are 50% more likely to deliver spontaneously at <35 weeks. CONCLUSION: In twin pregnancies, weight gain below recommended guidelines determined by maternal PPBMI is associated with higher rates of spontaneous preterm delivery at <35 weeks.