Gestational weight change in a diverse pregnancy cohort and mortality over 50 years: a prospective observational cohort study.

Background: High weight gain in pregnancy is associated with greater postpartum weight retention, yet long-term implications remain unknown. We aimed to assess whether gestational weight change was associated with mortality more than 50 years later.

Methods: The Collaborative Perinatal Project (CPP) was a prospective US pregnancy cohort (1959-65). The CPP Mortality Linkage Study linked CPP participants to the National Death Index and Social Security Death Master File for vital status to 2016. Adjusted hazard ratios (HRs) with 95% CIs estimated associations between gestational weight gain and loss according to the 2009 National Academy of Medicine recommendations and mortality by pre-pregnancy BMI. The primary endpoint was all-cause mortality. Secondary endpoints included cardiovascular and diabetes underlying causes of mortality.

Findings: Among 46 042 participants, 20 839 (45·3%) self-identified as Black and 21 287 (46·2%) as White. Median follow-up time was 52 years (IQR 45-54) and 17 901 (38·9%) participants died. For those who were underweight before pregnancy (BMI <18·5 kg/m²; 3809 [9·4%] of 40 689 before imputation for missing data]), weight change above recommendations was associated with increased cardiovascular mortality (HR 1·84 [95% CI 1·08-3·12]) but not all-cause mortality (1·14 [0·86-1·51]) or diabetes-related mortality (0·90 [0·13-6·35]). For those with a normal pre-pregnancy weight (BMI 18·5-24·9 kg/m²; 27 921 [68·6%]), weight change above recommendations was associated with increased all-cause (HR 1·09 [1·01-1·18]) and cardiovascular (1·20 [1·04-1·37]) mortality, but not diabetes-related mortality (0·95 [0·61-1·47]). For those who were overweight pre-pregnancy (BMI 25·0-29·9 kg/m²; 6251 [15·4%]), weight change above recommendations was associated with elevated all-cause (1·12 [1·01-1·24]) and diabetes-related (1·77 [1·23-2·54]) mortality, but not cardiovascular (1·12 [0·94-1·33]) mortality. For those with pre-pregnancy obesity (≥30·0 kg/m²; 2708 [6·7%]), all associations between gestational weight change and mortality had wide CIs and no meaningful relationships could be drawn. Weight change below recommended levels was associated only with a reduced diabetes-related mortality (0·62 [0·48-0·79]) in people with normal pre-pregnancy weight.

Interpretation: This study's novel findings support the importance of achieving healthy gestational weight gain within recommendations, adding that the implications might extend beyond the pregnancy window to long-term health, including cardiovascular and diabetes-related mortality.

Funding: National Institutes of Health.