The Origins of Sex Imbalance in Early Age Mortality

Roland Pongou, Brown University

Sex difference in mortality during infancy and childhood is decomposed into the effects of pre-birth environmental factors, child biology, and parental preferences. Exploiting variation in sex difference in mortality in the population of twins and within male-female twin pairs, and variation in parental bias in sub-Saharan Africa and India, we show that : (1) pre-birth environmental factors account for a large fraction of the higher mortality rates generally observed among males in the general population; (2) male biological make-up contributes to the elevated mortality of male children only during infancy, but its role has been previously overstated; however, contrary to the long-held biological theory of sex gap in morbidity and mortality, male biological make-up favors male survival during childhood; (3) parental discrimination against females increases mortality in this sex in India, but usual estimates of sex gap understate its effect by 400 percent during infancy, and 150 percent during childhood.