The association of inadequate mid-pregnancy weight gain and preterm birth in twin pregnancies

Objective:to determine whether inadequate gestational weight gain in the second trimester in twin pregnancies is associated with an increased risk of preterm birth (ptb) at <32 weeks.study design:retrospective cohort study including 489 twin pregnancies delivered between 2001 and 2013. rates of weight gain at different gestational ages were compared with institute of medicine guidelines.result:an inadequate rate of weight gain at <20 weeks was not associated with ptb. patients with inadequate rates of weight gain at 20 to 28 weeks had a higher risk of ptb at <32 weeks (37.6%) compared to those with adequate weight gain (15.2%) (p<0.001). in multivariate analysis, women with inadequate weight gain at 20 to 28 weeks were 2.8 times more likely to deliver at <32 weeks (95% confidence interval 1.65 to 4.81).conclusion:inadequate gestational weight gain at 20 to 28 weeks in twin pregnancies was the strongest predictor of ptb at <32 weeks. this represents an optimal time for interventions to improve weight gain and potentially decrease rates of ptb.