Energy intake and physical activity over the course of pregnancy and gestational weight gain: a systematic review and dose-response meta-analysis of data from randomized controlled lifestyle intervention trials.

Background: This systematic review and meta-analysis aimed to quantify the relationship between energy intake (EI) and physical activity (PA) during pregnancy and gestational weight gain (GWG) in randomized controlled trials (RCTs).

Methods: RCTs measuring EI and PA at least twice and total GWG during pregnancy were eligible. To synthesize PA measures reported on different scales, standardized mean change per day (SMC/day) were obtained by dividing the change in PA by the standard deviation of the change. We estimated mean changes in EI, PA, and mean total GWG across studies, accounting for clustering within studies. One-stage dose-response meta-analyses (DRMA) quantified the additional GWG associated with changes in EI and PA during pregnancy.

Results: A total of 21 RCTs with 7,705 participants were included. The mean total GWG was 11.99 kg (95% CI: 11.05 kg to 12.94 kg). The mean baseline EI was 1977 kcal/day across studies (range: 1652 to 2777 kcal/day) and the mean increase in EI throughout pregnancy was 132 kcal/day (95% CI: 54 to 209 kcal/day). The average change in PA during pregnancy was - 0.11 SMC/day (95% CI: -0.33 to 0.12 SMC/day). DRMA indicated 0.30 kg additional weight gain per 100 kcal/day increase in EI (95% CI: -0.01 kg to 0.60 kg, P = 0.06). The effect size was greater in studies with low risk of bias vs. high risk of bias (0.57 vs. -0.20 kg, P for difference = 0.02). DRMA showed 0.24 kg less weight gain per 0.25 SMC/day increase in PA (-0.50 to 0.02 kg, P = 0.07).

Conclusions: Average GWG often exceeds recommendations of current guidelines, particularly among women with overweight/obesity (OWOB), while average increases in EI were below current recommendations, and PA levels were frequently observed to decrease. DRMA further suggests that GWG may be modifiable through changes in EI and PA with greater EI increases or PA reductions linked to greater GWG, especially among women with OW/OB. Despite challenges in precisely quantifying these associations, integrated findings from this comprehensive systematic review and subgroup/sensitivity analyses highlight the need for more individualized nutrition and exercise recommendations and may warrant revisiting current guidelines.