Perinatal outcomes based on the institute of medicine guidelines for weight gain in twin pregnancies.

OBJECTIVE: To estimate the impact of the Institute of Medicine's (IOM) weight gain recommendations on perinatal outcomes in twin pregnancies.
METHODS: In this multicenter cohort study, using the 2009 IOM guidelines, we examined pregnancy outcomes in 570 uncomplicated diamniotic twin pregnancies. Subjects were grouped according to pre-pregnancy body mass index. Perinatal outcomes were assessed based on whether maternal weekly weight gain was less than, at, or in excess of the recommended IOM guidelines.
RESULTS: In women with a normal pre-pregnancy BMI, patients whose weight gain met the IOM recommendations had a significantly higher mean gestational age at delivery; less prematurity and larger birth weight infants compared to women whose weekly weight gain was less or excess than the recommended IOM guidelines. Similarly, when compared with their low weight gain counterparts, overweight women with appropriate weight gain had improved outcomes including higher mean gestational age at delivery, higher birth weight infants and less prematurity. In obese women, the amount of pregnancy weight gain did not impact perinatal outcomes.
CONCLUSION: Our results confirm that weekly maternal weight gain according to the IOM guidelines results in improved outcomes in twin pregnancies. Importantly, women with a normal or overweight pre-pregnancy BMI whose weekly weight gain was less than recommended, had increased risks of prematurity and lower birth weight infants. Similarly, women with a normal pre-pregnancy BMI whose weekly weight gain was excess than recommended had increased risks of prematurity and lower birth weight infants.