Birth weight, cognitive development, and life chances: A comparison of siblings from childhood into early adulthood

Using data from the National Longitudinal Survey of Youth Child Sample (CNLSY79), we sought to elaborate the complex interplay between childhood health and educational development over the early life course. Our approach made use of sibling comparisons to estimate the relationship between birth weight, cognitive development, and timely high school completion in models that spanned childhood, adolescence, and into early adulthood. Our findings indicated that lower birth weight, even after adjusting for fixed-family characteristics and aspects of the home environment that varied between siblings, was associated with decreased cognitive skills at age 5 and marginally significantly slower growth rates into adolescence. In addition, low birth weight increased the risk of not graduating by age 19, although this relationship reflected differences in cognitive development. Additional moderation analyses provided no evidence that birth weight effects are exacerbated by social conditions. Overall, the pattern of findings painted a complex picture of disadvantage, beginning in the womb and presumably via educational attainment, extending over the life course.