Abstract: Objective To explore changing trend and risk factors of birth defects and to analyze the contribution of prenatal screening and different diagnostic methods to the reduction of birth defects.Methods Data on 3416 registered birth defect cases and related perinatal records from 1st quarter of 1995 to 3rd quarter of 2014 were collected from birth defect monitoring system and obstetric service quality surveillance records of Beijing Dongcheng Maternal and Children Health Care Hospital.Excel 2007 was applied in statistical analysis.Results During the 20-year period, the annual incidence of perinatal birth defects in the district fluctuated smoothly, with a range from 9.4‰ to 19.8‰ and a median of 14.8‰;the annual incidence of total birth defects, including birth defects in second trimester induction, ranged from 9.4‰ to 38.2‰ and was slightly higher than the perinatal birth defects, with a median of 20‰.For all the birth defects, the proportion of congenital heart disease was the highest, with the annual ratios of 17%-22% and the annual ratios of birth defect of male fetuses(54%-55%) were significantly higher than those of female fetuses(37%-44%).Conclusion The annual incidence of birth defects in Dongcheng district from 1995 to 2014 showed a normal distribution and a slightly upward trend.The prenatal diagnosis rate of the birth defects in the district was improved steadily.Ultrasonography, amniocentesis, and chromosome analysis are still basic and relatively reliable methods for the prenatal diagnosis of birth defects.