Dr. C. Mary Schooling, professor at the CUNY Graduate School of Public Health and Health Policy, and colleagues examined the effect of birth weight on academic performance. The findings were published in the American Journal of Epidemiology.
Observationally, lower birth weight is usually associated with poorer academic performance; whether this association is causal or the result of confounding is unknown. To investigate this question, the research team obtained an effect estimate, which can have a causal interpretation under specific assumptions, of birth weight on educational attainment. The team used instrumental variable analysis based on single nucleotide polymorphisms determining birth weight, combined with results from the Social Science Genetic Association Consortium study of 126,559 Caucasians.
The research team obtained a similar estimate of the effect of birth weight on academic performance in 4,067 adolescents from Hong Kong’s (Chinese) Children of 1997 birth cohort (1997-2016), using twin status as an instrumental variable. Birth weight was not associated with years of schooling or college completion. Birth weight was also unrelated to academic performance in adolescents using instrumental variable analysis, although conventional regression gave a small positive association.
The team concluded that observed associations of birth weight with academic performance may not be causal, suggesting that interventions should focus on the contextual factors generating this correlation.
Shi Lin Lin, Gabriel Matthew Leung, C. Mary Schooling; The Effect of Birth Weight on Academic Performance: Instrumental Variable Analysis. Am J Epidemiol 2017; 185 (9): 853-859. doi: 10.1093/aje/kwx034