Passive Smoking and Preterm Birth in Urban China

Preterm birth is the leading cause of neonatal deaths and is also associated with well-known infant morbidities. Although the effects of active smoking during pregnancy are recognized, evidence for the effects of passive smoking is mixed. In China, 3.2 of women and 48.9 of men are active smokers, which offers a unique opportunity for studying passive smoking and reproductive health in nonsmoking women. This cohort study was undertaken to examine the association between passive smoking and preterm birth by clinical subtypes.