Becoming a parent: A systematic review and meta-analysis of changes in BMI, diet, and physical activity.

Abstract

Obesity prevalence rises fastest during young adulthood when weight, diet and physical activity may be influenced by life events, including becoming a parent, but the impact is uncertain. We searched six electronic databases to July 2019 for longitudinal studies (both sexes) aged 15-35y with a prospective pre-pregnancy/parenthood and post-delivery outcome. Of eleven studies (across 15 papers), 6 studies (women-only) were eligible for meta-analysis of the difference in change in body mass index (BMI; kg/m2) between remaining without children and becoming a parent. Mean(±SD) BMI gain for non-mothers was 2.8±1.3 kg/m2 (~7.5kg for 164cm woman) over 5.6±3.1y; 12.3% of baseline BMI (22.8±2.5kg/m2). Becoming a mother was associated with an additional BMI increase of 0.47±0.26kg/m2 (~1.3 kg), 4.3% of baseline BMI (22.8±5.6kg/m2); the one study including men reported no difference in change. Physical activity results were equivocal; 2/4 studies (women) and 2/2 (men) showed a greater decline in parents versus non-parents; diet (3 studies) varied by dietary measure, mostly indicating no difference. Becoming a mother is associated with 17% greater absolute BMI gain than remaining childless. Motherhood BMI gain is additional to an alarming BMI increase among young women, highlighting the need for obesity prevention among all young women, including mothers.