Thirty-six randomised controlled trials were included in this systematic review (n=12,526 women). The mean (SD) age of the participants was 30 years (5.1). The trials included interventions based on diet, physical activity, or a mixed approach of diet, physical activity, and behavior modifying techniques. About 45% of the women included were nulliparous, 40% were obese, and a similar proportion were classified as sedentary. Methodological quality of the included trials was assessed for sequence generation, allocation concealment, blinding, incomplete outcome data, selective outcome reporting, and other potential sources of bias. The primary outcomes were gestational weight gain, a composite of maternal outcomes, and a composite of children outcomes. The secondary outcomes were individual maternal and children complications.
For gestational weight gain, the intervention group reported less weight gain than the control group (mean difference (MD) -0.70 kg, 95% confidence interval (CI) -0.92 to -0.48 kg, 33 studies, 9,320 women). Differences in maternal and children composite outcomes were not statistically significant (maternal: odds ratio (OR) 0.90, 95% CI 0.79 to 1.03, 24 studies, 8,852 women; children: OR 0.94, 95% CI 0.83 to 1.08, 18 studies, 7,981 women). For the secondary outcomes, there was strong evidence for a reduction in the odds of caesarean section favouring the intervention group (OR 0.91, 95% CI 0.83 to 0.99, 32 studies, 11,410 women), but not for other individual complications. There is no evidence that effects differ across subgroups of women. In conclusion, diet and physical activity based interventions during pregnancy reduce gestational weight gain and lower the odds of caesarean section.
The International Weight Management in Pregnancy (i-WIP) Collaborative Group. Effect of diet and physical activity based interventions in pregnancy on gestational weight gain and pregnancy outcomes: meta-analysis of individual participant data from randomised trials. BMJ 2017;358:j3119.