ABSTRACT: Increased maternal weight or excessive weight gain in pregnancy is associated with adverse maternal and fetal outcomes. Existing reviews and guidelines making recommendations for interventions to manage weight gain in pregnancy are of limited value because of the small number of studies included. The best intervention that optimizes outcomes for the mother and baby has not been identified. Moreover, there is no consensus on what the desired outcomes are.
This systematic review and meta-analysis assessed the effects of dietary and lifestyle interventions in pregnancy on maternal and fetal weight and ranked the importance of these interventions on obstetric outcomes. A search of major databases was conducted from inception of the study until January 2012 to identify relevant randomized controlled trials evaluating any dietary or lifestyle interventions that could influence maternal weight during pregnancy and affect maternal and fetal outcomes related to weight. A search was also conducted for pertinent unpublished studies. Relative risks (RRs) were calculated for dichotomous data, and mean differences for continuous data.
A total of 44 relevant trials involving 7278 women were identified that evaluated the effects of 3 categories of interventions in pregnancy: diet, physical activity, and a mixed approach. Compared with controls, any intervention was associated with a reduced weight gain of 1.42 kg (95% confidence interval [CI], 0.95–1.89 kg; P < 0.001).
For combined interventions, there were no significant differences in birth weight from controls (mean difference, −50 g; 95% CI, −100 to 0 g), or in the incidence of babies large for gestational age (RR, 0.85; 95% CI, 0.66–1.09) and small for gestational age (RR, 1.00; 95% CI, 0.78–1.28). However, physical activity by itself was associated with reduced birth weight (mean difference, −60 g; 95% CI, −120 to −10 g; P = 0.02). Interventions resulted in a significant reduction in the risk of preeclampsia (RR, 0.74; 95% CI, 0.60–0.92) and shoulder dystocia (RR,0.39; 95% CI, 0.22–0.70). There was no significant effect of interventions on other critically important outcomes. Compared with other interventions, the largest reduction in weight gain occurred with dietary intervention (mean difference, 3.84 kg; 95% CI, 2.45–5.22 kg; P < 0.001), with improved pregnancy outcomes. The evidence rating for important clinical outcomes such as preeclampsia, gestational diabetes, gestational hypertension, and preterm delivery was low to very low.
These findings show that dietary and lifestyle interventions in pregnancy can reduce maternal gestational weight gain and are associated with improved outcomes for both mother and baby. Interventions based on diet are the most effective, with the greatest reduction in weight gain in pregnancy and with improved outcomes.