Abstract: Polycyclic aromatic hydrocarbons (PAHs) are some of the most important environmental contaminants, mainly from incomplete combustion of coal, automobile exhausts, cooking fume and tobacco smoking. Recently, a number of studies showed that PAHs could pass through the placental barrier, and the exposure levels of PAHs were correlated with the adverse birth outcome of infants. This article reviews the research progress on the birth outcome of PAHs exposure and the possible mechanisms. The research prospects are also discussed.