Weight Gain in Twin Pregnancies and Adverse Outcomes Examining the 2009 Institute of Medicine Guidelines

OBJECTIVE: To estimate whether the weight gain recommendations for twin pregnancies in the 2009 Institute of Medicine (IOM) guidelines are associated with improved perinatal outcomes. METHODS: A cohort of 297 twin pregnancies was identified from a single practice with measured prepregnancy body mass index (BMI) and weight gain during pregnancy. Recommended IOM guidelines were applied to our cohort based on prepregnancy BMI categories (normal weight, overweight, obese). Pregnancy outcomes were compared between patients whose weight gain met or exceeded the IOM recommendations and patients who did not meet these recommendations. RESULTS: Patients with normal prepregnancy BMIs whose weight gain met the IOM recommendations had significantly improved outcomes compared with patients who did not meet the IOM recommendations. They were less likely to have preterm birth before 32 weeks (5.0% compared with 13.8%) and spontaneous preterm birth before 32 weeks (3.4% compared with 11.5%). They also delivered significantly larger neontates (larger twin birth weight 2,582.1 +/- 493.4 g compared with 2,370.3 +/- 586.0 g; smaller twin birth weight 2,277.0 +/- 512.1 g compared with 2,109.3 +/- 560.9 g) and were significantly more likely to have both neonates weigh more than 2,500 g (38.8% compared with 22.5%) and more than 1,000 g (97.5% compared with 91.2%) and were less likely to deliver any twin with a birth weight lower than the fifth percentile for gestational age (21.5% compared with 35.0%). CONCLUSION: In women with twin pregnancies and normal starting BMIs, weight gain during pregnancy is significantly associated with improved outcomes, including a decreased risk of prematurity and larger birth weights. (Obstet Gynecol 2010;116:100-6)