Despite increasing evidence on the importance of in-utero air pollution exposure on later-life economic outcomes, little is known about the mechanisms underlying such effects. This paper examines the impacts of fetal exposure to air pollution in critical prenatal windows on child development using a panel administrative data on over 1,800 children and their mothers from Southern Shaanxi Province, China from the year 2013-2015, combined with a flexible fixed effects regression strategy. Then, I assess how micronutrients might moderate such impacts induced by prenatal exposure to PM2.5. I find that fetal air pollution exposure in the second trimester of pregnancy significantly reduces children’s later performance on the Bayley Mental Development Index and Bayley Psychomotor Development Index. Further, the micronutrient treatment moderates roughly one-third the damages induced by exposure to PM2.5.