The China-Anhui Birth Cohort Study (C-ABCS) was set up to examine the delayed, cumulative and interactive effects of maternal environmental exposures on birth outcomes and children's development. The C-ABCS recruited pregnant women from six major cities of Anhui province, China, between November 2008 and October 2010. A range of data (including demographic, obstetric, occupational, nutritional and psychosocial factors) were collected by both interviews and laboratory tests. In each trimester, women's blood samples were drawn, and pregnancy complications were abstracted from physician's medical records. By the end of 2011, birth outcomes/birth defects were observed/identified by clinicians within 12 months after the delivery of 11,421 singleton live births of six cities and those outcomes among the remaining 2033 live births are still being observed. In addition, 4668 children from Ma'anshan city will be further followed up during the pre-school period till they reach adolescence to obtain the data on familial environmental exposures as well as children's physical, psychological, behavioural and sexual development. The interview data and information on laboratory examinations are available on request from archives in the Anhui Provincial Key Laboratory of Population Health & Aristogenics.