There is not enough evidence to recommend any intervention for preventing excessive weight gain during pregnancy, due to the significant methodological limitations of included studies and the small observed effect sizes. More high-quality randomised controlled trials with adequate sample sizes are required to evaluate the effectiveness of potential interventions.
Randomized trial of a behavioral intervention to prevent excessive gestational weight gain: the Fit for Delivery Study.
Excessive weight gain during pregnancy is a major risk factor for postpartum weight retention and future weight gain and obesity in women, but few adequately powered randomized controlled trials have examined the efficacy of a behavioral weight-control intervention during pregnancy.
                This study examined whether a behavioral intervention during pregnancy could decrease the proportion of women who exceeded the 1990 Institute of Medicine (IOM) recommendations for gestational weight gains and increase the proportion of women who returned to pregravid weights by 6 mo postpartum.
                This study was a randomized, assessor-blind, controlled trial. Participants were pregnant (13.5 wk gestation), normal-weight (NW; n = 201) and overweight or obese (OW/OB; n = 200) women whose average age was 28.8 y. Participants were randomly assigned within the 1990 IOM weight category (NW compared with OW/OB) to standard care (n = 200) or to a behavioral intervention to prevent excessive gestational weight gain (n = 201). The intervention included one face-to-face visit; weekly mailed materials that promoted an appropriate weight gain, healthy eating, and exercise; individual graphs of weight gain; and telephone-based feedback. The retention at the 6-mo postpartum assessment was 82%.
                Intent-to-treat analyses showed that the intervention, compared with standard care, decreased the percentage of NW women who exceeded IOM recommendations (40.2% compared with 52.1%; P = 0.003) and increased the percentages of NW and OW/OB women who returned to their pregravid weights or below by 6 mo postpartum (30.7% compared with 18.7%; P = 0.005).
                A low-intensity behavioral intervention during pregnancy reduced excessive gestational weight gains in NW women and prevented postpartum weight retention in NW and OW/OB women. This trial was registered at clinicaltrials.gov as NCT01117961.