Prenatal Smoking Cessation and Infant Health: Evidence from Sibling Births

This paper uses a unique large panel data of sibling births to provide new evidence on when prenatal smokers must quit smoking to deliver the healthy newborn. In a series of the mother fixed effect estimation, I find robust results that early cessation in the first trimester nullifies the adverse smoking impact, but late cessation in the second trimester still leaves a remarkably irreversible damage on infant health. About two third of the adverse smoking impact on infant health occurs in the second trimester, mainly through fetal growth retardation. Therefore the first trimester is the critical period for prenatal smoking cessation. In particular, failing to stop smoking promptly in this period is crucial to explain why low socioeconomic status prenatal smokers transmit their poor health and economic status to the offspring. The policy implication is that reallocating resources on prenatal smoking cessation towards the first trimester can lead to a significant effciency gain. This paper also uncovers a new source of downward bias in estimating the causal relation between a group measure prenatal smokers and infant health, if the timing information of smoking cessation is misused. Key Words: Prenatal Smoking, Timing of Smoking Cessation, Birth Weight, Low Birth Weight