Abstract: Objective To understand the incidence of birth defects in Dinghai and explore the related risk factors. Methods The data of the birth defects surveillance and prenatal health care surveillance from January 2004 to December 2007 in Dinghai were analyzed. Results From 2004 to 2007, a total of 9236 infants were under birth defect surveillance, and 133 cases of birth defects were reported. The average annual incidence of birth defects was 144.00/lakh. The incidence rate increased by years. The first five birth defects with high incidences were congenital heart disease, external ear malformation, polydactylia, cleft lip with or without cleft palate and congenital hydrocephalus. By stepwise logistic regressions model, it was found that urine protein, dysmenorrhea, husband education level, husband smoking history were included in the model. Compared with the pregnant women whose husbands were with education level of junior middle school or lower, those whose husband were with higher education level of university were at higher risk to deliver infants with birth defects , and compared with the pregnant women whose husbands didnt smoke, those whose husbands smoked were at higher risk to deliver infants with birth defects. . Conclusion The risk factors for birth defects included non-agricultural occupation, husbands smoking history and syphilis. The health education about birth defects prevention should be strengthened to promote health lifestyle, reduce occupational exposure, and the screening of high-risk groups should be strengthened to reduce the birth defects.