Coal smoke, gestational cadmium exposure, and fetal growth.

•Ulaanbaatar, Mongolia has poor air quality due primarily to coal smoke from home heating stoves.•Emissions from coal stoves may be an important source of cadmium exposure in this population.•Maternal blood cadmium concentrations were associated with lower birth weight.•In some settings, cadmium may play a role in the putative association between air pollution and fetal growth.