SISTERS, SIBLINGS, AND MOTHERS - THE EFFECT OF TEENAGE CHILDBEARING ON BIRTH OUTCOMES IN A DYNAMIC FAMILY CONTEXT

A statistical model of dynamic intrafamily investment behavior incorpo rating endowment heterogeneity is estimated to evaluate alternative es timation procedures that have exploited family and kinship data. These procedures, which place alternative restrictions on the endowment str ucture and on behavior, include generalized least squares, instrumenta l-variables, fixed-effects based on the children of sisters, fixed-eff ects based on siblings, and sibling fixed-effects with instrumental va riables. The framework is applied to data on birth outcomes, with focu s on the effects of teen-age childbearing net of other maternal behavi or. The empirical results imply that the least restrictive statistical formulation, consistent with dynamic behavior and heterogeneity among siblings, fits the data best. All of the estimation procedures that c ontrol for a family-specific endowment indicate, however, that the bio logical effect of having a birth at younger ages is to marginally incr ease birthweight and to increase fetal growth.