Neonatal Health, Birth Weight, and Early Childhood Cognitive Outcomes: Variation in Effects by Socioeconomic Status

• In Event: 3-004 - Studying the Prenatal and Neonatal Environments and their Effects on Development Using Secondary data

Abstract

Numerous studies have linked poor neonatal health, typically measured by low birth weight (LBW), with delayed cognitive outcomes in childhood. However, these studies have typically employed correlational methods that compare unrelated children who differ in birth weight (BW). This approach leaves open the possibility that it is not LBW that causes poorer cognitive outcomes, but rather some other factor-such as family disadvantage or maternal stress-that causes both LBW and child outcomes.
Further, previous studies have not examined whether these associations between BW and child outcomes differ by socioeconomic status (SES). This is important because if the negative influence of LBW on child outcomes is stronger for low-SES children, this puts these children-who are already at greater risk for LBW and poorer developmental outcomes-at even greater disadvantage.
In this study, we are able to take a more causal approach to the question of whether BW predicts poorer cognitive outcomes by comparing siblings whose birth weights differ. Data are drawn from the National Longitudinal Survey of Youth 1979 (NLSY) and the Early Childhood Longitudinal Study-Birth Cohort (ECLS-B), the only nationally representative samples that contain rich data on neonatal health, child outcomes, and siblings. The NLSY gathered data on siblings, while the ECLS-B sibling sample consists exclusively of twins. Sibling pairs from each dataset are then used in sibling fixed-effects models that control for unobserved family characteristics that do not vary between siblings and that typically bias the association between BW and child outcomes in correlational OLS models. Further, we ran separate models using different indicators neonatal health, such as fetal growth rate, that more accurately capture the relationship with cognitive outcomes than BW alone, and controlled for a robust set of sibling and maternal characteristics that differ between children (e.g., gender, birth order, mother's prenatal health). Child cognitive outcomes were taken at school entry and included math and reading subscales of the PIAT and the PPVT in the NLSY, and survey specific assessments developed for the ECLS-B.
Both datasets show strong negative within family effects of neonatal health at birth on cognitive outcomes, especially for math (see Table 1). However, when examining how the relationships differ by SES, the findings are less conclusive. The NLSY suggests that the findings are consistent across SES, while the ECLS-B suggests they are not. In the ECLS-B, the effects of BW are significantly stronger for children of less educated mothers.

Authors

• Caitlin Hines, Georgetown University
  Presenting Author

• Christina M Padilla, Georgetown University

• Rebecca Ryan, Georgetown University