Separated at Girth: US Twin Estimates of the Effects of Birth Weight

Heather Royer
2009 American Economic Journal: Applied Economics  
The fetal origins hypothesis asserts that nutrient deprivation in utero can raise an individual's chronic disease risk. Within economics, this hypothesis has gained acceptance as a leading explanation for the cross-sectional correlations between birthweight, a proxy for fetal nutrient intake, and adult outcomes such as educational attainment, earnings and health. However, tests of this hypothesis using crosssectional data may not adequately account for the effect of omitted variables such as
more » ... ily background and genetics on these outcomes. To estimate the effects of birthweight while controlling for these factors, I exploit differences in birthweight between twins. I use two datasets on twins: a newly-created dataset, consisting of over 3,000 twin pairs, coming from the universe of 1960-1982 California birth records and the Early Childhood Longitudinal Study-Birth Cohort. Using these data, I find that birthweight is related to educational attainment, later pregnancy complications, and the birthweight of the next generation. With the exception of pregnancy complications, however, the effects of birthweight are small, especially in relation to recent findings for other countries -raising questions about the long-run returns to pre-birth interventions that increase birthweight. JEL codes: I1, I2
doi:10.1257/app.1.1.49 fatcat:b2pvqearnneuvajgcrb4z5t6wy