Association of Gestational Weight Gain With Adverse Maternal and Infant Outcomes

Importance: Both low and high gestational weight gain have been associated with adverse maternal and infant outcomes, but optimal gestational weight gain ranges remain uncertain and not well defined for all pre-pregnancy weights. Objective: To examine the association of ranges of gestational weight gain with risks of adverse maternal and infant outcomes and to estimate optimal gestational weight gain ranges across a range of pre33 pregnancy weights. Design, Setting, and Participants: Individual participant data meta-analysis using data from 196670 participants from 25 cohort studies from Europe and North-America (main study-sample). Optimal gestational weight gain ranges were estimated for each pre-pregnancy BMI category by selecting the range of gestational weight gain that was associated with lower risk for the main endpoint, defined as ‘any adverse outcome’. Individual participant data from 3505 participants from 4 separate hospital-based cohorts were used as validation sample. Data were collected between 1989 and 2015. Final date of follow-up was December 2015. Exposures: Gestational weight gain. Main Outcomes and Measures: ‘Any adverse outcome’, defined as the presence of one or more of the following outcomes: pre-eclampsia, gestational hypertension, gestational diabetes, caesarean section, preterm birth, small or large size-for-gestational-age at birth. Results: Of the 196670 women included in the main sample, 7809 (4.0%), 133788 (68.0%), 38828 (19.7%), 11992 (6.1%), 3284 (1.7%) and 969 (0.5%) were underweight, normal weight, overweight, obesity grade 1, obesity grade 2 and obesity grade 3 at baseline, respectively. Overall, any adverse outcome occurred in 37.2% (n=73161) of women, ranging from 34.7% (n=2706) in women with underweight to 61.1% (n=592) in women with obesity grade 3. Optimal weight gain ranges were 14.0-50 <16.0 kg for underweight, 10.0-<18.0 kg for normal weight, 2.0-<16.0 kg for overweight, 2.0-<6.0 kg for 51 obesity grade 1, weight loss- weight gain of <4.0 kg for obesity grade 2, and 0.0-<6.0 kg for obesity grade 3. These ranges were associated with low to moderate discrimination between those with and without adverse outcomes (Areas-under-the-curve (AUCs): 0.546-0.759). Results for discriminative performance in the validation sample were similar to corresponding results in the main study-sample (AUCs: 0.506-0.787). Conclusions and Relevance: In this meta-analysis of pooled individual participant data from 25 cohort studies, the risk of adverse maternal and infant outcomes varied by gestational weight gain and across the range of pre-pregnancy weights. The estimates of optimal gestational weight gain may inform prenatal counseling, although the optimal weight gain ranges had limited predictive value for the outcomes assessed.