摘要：Objectives. We sought to determine if and to what extent a woman’s exposure to stressful life events prior to conception (PSLEs) were associated with subsequent infant birth weight by using a nationally representative sample of US women. Methods. We examined 9350 mothers and infants participating in the first wave of the Early Childhood Longitudinal Study, Birth Cohort in 2001. Weighted regressions estimated the effect of exposure on very low and low birth weight, adjusting for maternal sociodemographic and health factors and stress during pregnancy. Results. Twenty percent of women experienced any PSLE. In adjusted analyses, exposed women were 38% more likely to have a very low birth weight infant than nonexposed women. Furthermore, the accumulation of PSLEs was associated with reduced infant birth weight. Conclusions. This was the first nationally representative study to our knowledge to investigate the impact of PSLEs on very low and low birth weight in the United States. Interventions aimed to improve birth outcomes will need to shift the clinical practice paradigm upstream to the preconception period to reduce women’s exposure to stress over the life course and improve the long-term health of children. Disorders related to very low birth weight and low birth weight (LBW) are the leading cause of all neonatal deaths in the United States 1 and contribute substantially to childhood and adult morbidity and mortality. 2–5 Reducing the prevalence of very LBW and LBW, which occurs in approximately 8.2% of births in the United States, 6 has significant implications for the future health and well-being of children and families, and is a national health priority. 7 However, despite extensive research, practice, and public health efforts devoted to reducing the number of children born with LBW, the prevalence of very LBW and LBW in the United States remains unacceptably high, suggesting that additional risk factors must be identified to improve outcomes. Maternal exposure to stress during pregnancy is an important contributor to LBW. 8–14 Furthermore, Danish population-based evidence suggests that exposure to stressors before pregnancy (i.e., severe life events, such as death or serious health problems of a relative) may also be associated with reduced infant birth weight. 15 This finding empirically supports theoretical literature that suggests that the accumulation of stress across the life course results in increased allostatic load or “weathering,” leading to a decline in reproductive health. 16,17 Other studies have linked affective states (e.g., depression), which has been hypothesized to be the result of acute or chronic stress, 18 during pregnancy to reduced fetal growth and birth weight. 19 Moreover, poor preconception mental health has been associated with an increased risk of LBW among a nationally representative cohort of US women and their babies. 20 However, to our knowledge, no study has investigated stressful life events prior to conception (PSLEs) as possible predictors of birth weight in a national sample of women living in the United States. Therefore, we used population-based data available from the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B) to determine if and to what extent a woman’s exposure to PSLEs were associated with having a very LBW or LBW infant. Findings from this study will provide critical information about preconception predictors of birth weight and have significant implications for approaches to preconception, interconception, and primary care. Understanding these pathways might also shift the focus of clinical practice earlier in the life course and inform upstream interventions to improve birth outcomes.
