Gestational Weight Change in a Diverse Pregnancy Cohort and Mortality Over 50 Years: A Prospective Observational Cohort Study

Weight gain during pregnancy that exceeds the recommendations updated by the National Academy of Medicine (NAM) in2009 has been associated with greater postpartum weight retention. One systematic review of 9 studies found an association between excessive weight gain during pregnancy and postpartum weight retention of 3.06 kg at 3 years and 4.72 kg at15 years. Greater gestational weight gain has also been associated with higher fat mass, greater waist circumference, and in-creased visceral adipose tissue. With evidence showing that excessive weight gain in midlife can lead to the development of cardiovascular (CV) diseases and diabetes, it may be hypothesized that, during pregnancy, higher weight gain may increase the risk of CV diseases and lower weight gain may lower that risk. No studies have examined the long-term risks of high weight gain during pregnancy. The aim of this study was to examine the associations between weight change during pregnancy and all-cause mortality up to 50 years postpregnancy. Data were obtained from The Collaborative Perinatal Project (CPP), an observational cohort study of pregnant people be-tween 1959 and 1966, and the CPP Mortality Linkage Study, which included participant vital status from 2016 onwards. Prepregnancy weight was self-reported by participants, and subsequent weight was recorded at each prenatal visit and at ad-mission for delivery. The primary outcome was all-cause mortality. Secondary outcomes included mortality due to CV disease or diabetes. All analyses were stratified by prepregnancy body mass index (BMI) categories: underweight (<18.5 kg/m(2)), normal weight (18.5 to 24.9 kg/m(2)), overweight (25 to 29.9 kg/m(2)), and obese (>= 30.0 kg/m(2)). Of the 40,689 participants in the CPP, 68.5% had normal prepregnancy BMI. Those who were classified as under weight prior to pregnancy had the highest mean weight change of 10.4 kg (standard deviation [SD], 4.0), whereas those who were obese prepregnancy had the lowest mean change of 6.5 kg (SD, 7.2). The median follow-up of participants was 52 years (interquartile range, 45-54), and 38.9% of 46,042 participants died. The rate of mortality per 1000 person-years rose as prepregnancy BMI increased (underweight: 6.6; 95% confidence interval [CI], 6.3 to 7.0; normal weight: 7.3; 95% CI, 7.1to 7.4; overweight: 10.5; 95% CI, 10.2 to 10.9; and obese: 14.4; 95% CI, 13.7 to 15.0). Among participants who were under-weight before pregnancy, weight change above the NAM recommendations was associated with increased CV mortality (hazards ratio [HR], 1.84; 95% CI, 1.08 to 3.12), but not all-cause or diabetes-related mortality. Among participants who were normal weight prepregnancy, there was an association between weight change below recommendations and decreased diabetes-related mortality (HR, 0.62; 95% CI, 0.48 to 0.79). Weight change above recommendations for normal weight participants was associated with increased all-cause (HR, 1.09; 95% CI, 1.01 to 1.18) and CV (HR, 1.20; 95% CI, 1.04-1.37)mortality. Among participants who were overweight before pregnancy, there were significant associations observed between weight change and all-cause (HR, 1.12; 95% CI, 1.01 to 1.24) and diabetes-related (HR, 1.77; 95% CI, 1.23 to 2.54) mortality, but not CV-related mortality. Among participants who were obese before pregnancy, no meaningful associations were observed between weight change during pregnancy and mortality as there were wide confidence intervals. In conclusion, this study examined weight change during pregnancy to long-term mortality. The study found that individuals who gain weight during pregnancy that exceeds the NAM recommendations may be at heightened risk of earlier mortality. Efforts are needed to help pregnant people achieve healthy weight gain during pregnancy and decrease the risk of mortality