Low birth weight (LBW, infants born weighing less than 2500 grams) is a major cause of infant mortality, morbidity, and developmental deficits. LBW has long been a public health concern in the US, in part because the LBW rate is higher in the US than in other rich nations. Concerns are now heightened, because the rate of LBW has risen 24% since the mid-1980s. In 2006, the rate reached 8.3%, its highest level in four decades. The reasons this rise remain elusive. Increases in multiple births over the past three decades account for a sizeable part of the increase among all births;however the rate of LBW also has increased among singletons. The increased rate of LBW is troubling not only because of the higher number of at-risk infants, but because the increased rate may be echoed in future birth cohorts. Previous studies have shown that mothers who were LBW are more likely to bear LBW offspring, suggesting that LBW is to some extent self-perpetuating. Interventions designed to interrupt the transmission of LBW between generations are thus critical to reducing both current and future rates. However, the processes underlying the intergenerational transmission of birth weight are not well understood. In particular, research demonstrating that family context can buffer the impact of LBW on developmental outcomes suggests that positive family contexts may also reduce the likelihood that mothers born LBW deliver LBW infants. Yet little research examines the impact of childhood family context on the likelihood that a woman born LBW will bear a LBW child. This study addresses this important gap by assessing whether and how childhood family context moderates the link between mother's birth weight and the birth weight of her offspring. It examines two dimensions of family context: socioeconomic circumstances, in particular family structure and family economic status, and family environment. The study leverages the complementary strengths of two longitudinal surveys, the Panel Study of Income Dynamics (PSID) and the Children of the National Longitudinal Study of Youth 1979 Cohort (CNLSY79). Both studies have followed respondents for many years and thus contain extensive information, collected contemporaneously, about women's lives from birth through the childbearing years, including information about their offspring. The analysis will be organized around three specific aims: 1) Evaluate the link between maternal and offspring birth weight in the PSID and CNLSY79;2) Determine whether and how the link between maternal and offspring birth weight is moderated by the socioeconomic circumstances experienced by the mother in childhood;3) Determine whether the link between maternal and offspring birth weight is moderated by the family environment experienced by the mother in childhood.
The results from this project will inform researchers, practitioners, and policy makers about the malleability of the intergenerational transmission of birth weight and the extent to which experiencing an advantaged family environment in childhood reduces the likelihood that a woman born LBW will bear a LBW child. Given current evidence that childhood experiences are positively related to lifetime well-being, the moderating effect of childhood family environment-and thus the potential for intervention to reduce current and future rates of LBW- may be substantial.
