Weight gain in twin gestations: are the Institute of Medicine guidelines optimal for neonatal outcomes?

To assess neonatal outcomes according to gestational weight gain (GWG) in twins.

This was a retrospective cohort study of twins delivered at ⩾24 weeks. GWG was defined using the Institute of Medicine (IOM) guidelines as the referent. Birthweight and neonatal intensive-care unit (NICU) admissions were compared with ≥(2)- and analysis of variance tests, stratified by body mass index (BMI).

In all three BMI groups, mean birth weight of the larger and smaller twin increased as GWG increased, P<0.01. For the underweight/normal-weight group, both twins <2500 g, <1500 g and small for gestational age decreased significantly as GWG increased. Birthweight <2500 g increased in all groups with GWG below the IOM guidelines, P<0.01. In the multivariate analysis, both twins <2500 g were significantly decreased with GWG above IOM guidelines. There was no difference in NICU admissions with GWG above the IOM guidelines.

GWG above the IOM guidelines may improve twin birth weights, with the findings most significant in underweight/normal-weight women.