摘要：Objectives. To model the hypothetical impact of preventing excessive gestational weight gain on midlife obesity and compare the estimated reduction with the US Healthy People 2020 goal of a 10% reduction of obesity prevalence in adults. Methods. We analyzed 3917 women with 1 to 3 pregnancies in the prospective US National Longitudinal Survey of Youth, from 1979 to 2012. We compared the estimated obesity prevalence between 2 scenarios: gestational weight gain as reported and under the scenario of a hypothetical intervention that all women with excessive gestational weight gain instead gained as recommended by the Institute of Medicine (2009). Results. A hypothetical intervention was associated with a significantly reduced estimated prevalence of obesity for first (3.3 percentage points; 95% confidence interval [CI] = 1.0, 5.6) and second (3.0 percentage points; 95% CI = 0.7, 5.2) births, and twice as high in Black as in White mothers, but not significant in Hispanics. The population attributable fraction was 10.7% (95% CI = 3.3%, 18.1%) in first and 9.3% (95% CI = 2.2%, 16.5%) in second births. Conclusions. Development of effective weight-management interventions for childbearing women could lead to meaningful reductions in long-term obesity. In 2011, the prevalence of obesity in adult US women overall was more than 30%, and was highest in non-Hispanic Black and Hispanic middle-aged women. 1 Prevention of weight gain is imperative because obesity is a risk factor for many diseases throughout the life course, and once established, is intractable. 2,3 Objective 9 of Healthy People 2020 calls for a 10% decrease in the obesity prevalence in adults aged 20 years and older (from 33.9% to 30.5%) by 2020. 4 In its 2009 report, the Institute of Medicine (IOM) concluded that excessive gestational weight gain (GWG) is common in US women, and strongly associated with maternal weight retention up to 3 years postpartum, but deemed the evidence for longer-term weight less conclusive. 5 Only 6 published studies have followed women more than 10 years after birth. 6–11 Although it is informative, current evidence is not based on nationally representative US samples, does not focus on disparities by race/ethnicity, includes only a single birth per mother rather than repeat pregnancies, and is not reported in a way that allows assessment of how excessive GWG might contribute to meeting the Healthy People 2020 goals for women who have given birth in the United States. To our knowledge, no experimental trials of gestational weight gain have followed women into midlife, which is not surprising given the costs and complexity of conducting an experimental intervention with such long-term follow-up. To address these gaps in knowledge, we estimated the reduction in obesity that could be expected if a theoretical intervention at the clinical or public health level 12,13 prevented all excessive GWG in US women, and compared our findings with Healthy People 2020 Objective 9. We used an analytical strategy based on the causal roadmap presented by Petersen and van der Laan, which outlines a principled step-by-step process that allows one to formulate and attempt to answer causal questions, while acknowledging limitations in data and methodology that prevent a casual interpretation of results. 14 We estimated the effect of GWG on obesity at age 40 years in the longitudinal cohort’s first, second, and third pregnancies, and investigated how its magnitude varied by pregnancy order, prepregnancy body mass index (BMI; defined as weight in kilograms divided by the square of height in meters), age at first birth, and race/ethnicity.
