The Association Between Second-Trimester Weight Gain and Preterm Birth in Twin Pregnancies

Abstract

INTRODUCTION: Our objective was to determine whether inadequate gestational weight gain in the second trimester in twin pregnancies is associated with an increased risk of preterm birth before 32 weeks of gestation. METHODS: We performed a retrospective cohort study including all viable twin pregnancies delivered at UCSD Medical Center from 2009-2013. Adequate gestational weight gain rates were calculated by dividing the 2009 Institute of Medicine-recommended minimum total gestational weight gain by 37 weeks. Student's t-test and the x2 test were used for bivariate analyses and logistic regression for multivariate analyses. RESULTS: One hundred sixty-nine twin pregnancies met inclusion criteria. Inadequate gestational weight gain at 20-28 weeks was associated with a significantly higher risk of preterm birth before 32 weeks (32% compared with 14%, P=.02) and spontaneous preterm birth before 32 weeks (26% compared with 9%, P=.01). Monochorionicity, cervical length less than 2.5 cm, and advanced maternal age were also significantly associated with preterm birth before 32 weeks. Multivariate analyses confirmed independent associations between inadequate gestational weight gain and cervical length less than 2.5 cm with preterm birth before 32 weeks (Table 1). CONCLUSIONS: Inadequate gestational weight gain at 20-28 weeks in twin pregnancies was the strongest predictor of preterm birth before 32 weeks. This may represent an optimal time for nutritional and counseling interventions to improve gestational weight gain and potentially decrease the rate of preterm birth. (Table Presented).