The effects of birth inputs on birthweight: evidence from quantile estimation on panel data

Unobserved heterogeneity among childbearing women makes it difficult to isolate the causal effects of smoking and prenatal care on birth outcomes (such as birthweight). Whether or not a mother smokes, for instance, is likely to be correlated with unobserved characteristics of the mother. This paper controls for such unobserved heterogeneity by using state-level panel data on maternally linked births. A quantile-estimation approach, motivated by a correlated random-effects model, is used in order to estimate the effects of smoking and other observables (number of prenatal-care visits, years of education, etc.) on the entire birthweight distribution. ∗Department of Economics, The University of Texas, Austin, TX 78712. †CREATES and School of Economics and Management, University of Aarhus, Aarhus, Denmark; e-mail: [email protected].