Interventions to reduce or prevent obesity in pregnant women: a systematic review.

BACKGROUND: Around 50% of women of childbearing age are either overweight [body mass index (BMI) 25-29.9 kg/m(2)] or obese (BMI ≥ 30 kg/m(2)). The antenatal period provides an opportunity to manage weight in pregnancy. This has the potential to reduce maternal and fetal complications associated with excess weight gain and obesity. OBJECTIVES: To evaluate the effectiveness of dietary and lifestyle interventions in reducing or preventing obesity in pregnancy and to assess the beneficial and adverse effects of the interventions on obstetric, fetal and neonatal outcomes. DATA SOURCES: Major electronic databases including MEDLINE, EMBASE, BIOSIS and Science Citation Index were searched (1950 until March 2011) to identify relevant citations. Language restrictions were not applied. REVIEW METHODS: Systematic reviews of the effectiveness and harm of the interventions were carried out using a methodology in line with current recommendations. Studies that evaluated any dietary, physical activity or mixed approach intervention with the potential to influence weight change in pregnancy were included. The quality of the studies was assessed using accepted contemporary standards. Results were summarised as pooled relative risks (RRs) with 95% confidence intervals (CIs) for dichotomous data. Continuous data were summarised as mean difference (MD) with standard deviation. The quality of the overall evidence synthesised for each outcome was summarised using GRADE (Grading of Recommendations Assessment, Development, and Evaluation) methodology and reported graphically as a two-dimensional chart. RESULTS: A total of 88 studies (40 randomised and 48 non-randomised and observational studies, involving 182,139 women) evaluated the effect of weight management interventions in pregnancy on maternal and fetal outcomes. Twenty-six studies involving 468,858 women reported the adverse effect of the interventions. Meta-analysis of 30 RCTs (4503 women) showed a reduction in weight gain in the intervention group of 0.97 kg compared with the control group (95% CI -1.60 kg to -0.34 kg; p = 0.003). Weight management interventions overall in pregnancy resulted in a significant reduction in the incidence of pre-eclampsia (RR 0.74, 95% CI 0.59 to 0.92; p = 0.008) and shoulder dystocia (RR 0.39, 95% CI 0.22 to 0.70; p = 0.02). Dietary interventions in pregnancy resulted in a significant decrease in the risk of pre-eclampsia (RR 0.67, 95% CI 0.53 to 0.85; p = 0.0009), gestational hypertension (RR 0.30, 95% CI 0.10 to 0.88; p = 0.03) and preterm birth (RR 0.68, 95% CI 0.48 to 0.96; p = 0.03) and showed a trend in reducing the incidence of gestational diabetes (RR 0.52, 95% CI 0.27 to 1.03). There were no differences in the incidence of small-for-gestational-age infants between the groups (RR 0.99, 95% CI 0.76 to 1.29). There were no significant maternal or fetal adverse effects observed for the interventions in the included trials. The overall strength of evidence for weight gain in pregnancy and birthweight was moderate for all interventions considered together. There was high-quality evidence for small-for-gestational-age infants as an outcome. The quality of evidence for all interventions on pregnancy outcomes was very low to moderate. The quality of evidence for all adverse outcomes was very low. LIMITATIONS: The included studies varied in the reporting of population, intensity, type and frequency of intervention and patient complience, limiting the interpretation of the findings. There was significant heterogeneity for the beneficial effect of diet on gestational weight gain. CONCLUSIONS: Interventions in pregnancy to manage weight result in a significant reduction in weight gain in pregnancy (evidence quality was moderate). Dietary interventions are the most effective type of intervention in pregnancy in reducing gestational weight gain and the risks of pre-eclampsia, gestational hypertension and shoulder dystocia. There is no evidence of harm as a result of the dietary and physical activity-based interventions in pregnancy. Individual patient data meta-analysis is needed to provide robust evidence on the differential effect of intervention in various groups based on BMI, age, parity, socioeconomic status and medical conditions in pregnancy.

Effects of interventions in pregnancy on maternal weight and obstetric outcomes: meta-analysis of randomised evidence.

OBJECTIVE: To evaluate the effects of dietary and lifestyle interventions in pregnancy on maternal and fetal weight and to quantify the effects of these interventions on obstetric outcomes. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Major databases from inception to January 2012 without language restrictions. STUDY SELECTION: Randomised controlled trials that evaluated any dietary or lifestyle interventions with potential to influence maternal weight during pregnancy and outcomes of pregnancy. DATA SYNTHESIS: Results summarised as relative risks for dichotomous data and mean differences for continuous data. RESULTS: We identified 44 relevant randomised controlled trials (7278 women) evaluating three categories of interventions: diet, physical activity, and a mixed approach. Overall, there was 1.42 kg reduction (95% confidence interval 0.95 to 1.89 kg) in gestational weight gain with any intervention compared with control. With all interventions combined, there were no significant differences in birth weight (mean difference -50 g, -100 to 0 g) and the incidence of large for gestational age (relative risk 0.85, 0.66 to 1.09) or small for gestational age (1.00, 0.78 to 1.28) babies between the groups, though by itself physical activity was associated with reduced birth weight (mean difference -60 g, -120 to -10 g). Interventions were associated with a reduced the risk of pre-eclampsia (0.74, 0.60 to 0.92) and shoulder dystocia (0.39, 0.22 to 0.70), with no significant effect on other critically important outcomes. Dietary intervention resulted in the largest reduction in maternal gestational weight gain (3.84 kg, 2.45 to 5.22 kg), with improved pregnancy outcomes compared with other interventions. The overall evidence rating was low to very low for important outcomes such as pre-eclampsia, gestational diabetes, gestational hypertension, and preterm delivery. CONCLUSIONS: Dietary and lifestyle interventions in pregnancy can reduce maternal gestational weight gain and improve outcomes for both mother and baby. Among the interventions, those based on diet are the most effective and are associated with reductions in maternal gestational weight gain and improved obstetric outcomes.