摘要Background:To investigate the surveillance trend of birth defects,incidence,distribution,occurrence regularity,and their relevant factors in Xi'an City in the last 10 years for proposing control measures.Methods:The birth defects monitoring data of infants during perinatal period (28 weeks of gestation to 7 days after birth) were collected from obstetrics departments of all hospitals during 2003-2012.Microsoft Excel 2003 was used for data input,and Statistical Package for the Social Sciences version 16.0 (International Business Machines Corporation,New York,NY,USA) was used for descriptive analysis.x2 test,Spearman correlation and linear-by-linear association trend test were used for statistical analyses.Results:The birth defect rate declined from 9.18％ in 2003 to 7.00％ in 2012 (x2 =45.00 l,P ＜ 0.01) with a mean value of 7.85％,which is below the Chinese national average level (x2 =20.451,P ＜ 0.01).The order of five most common birth defects has changed.The incidence of congenital heart disease (CHD) increased with time,particularly after 2012,it became the most frequent type (rs =0.808,P ＜ 0.001).Till then,the number of neural tube defects (NTDs) declined significantly (x2 =76.254,P ＜ 0.01).The average birth defects rate of 8.11％ in rural areas was higher than that in urban areas (7.56％,x2 =7.919,P ＜ 0.01) and much higher in males (8.28％) than that in females (7.18％,x2 =32.397,P ＜ 0.0 1).Maternal age older than 35 years (x2 =35.298,P ＜ 0.01) is the most dangerous age bracket of birth defects than maternal age younger than 20 years (x2 =7.128,P ＜ 0.0l).Conclusions:A downward trend of birth defects was observed in Xi'an City from 2003 to 2012.NTDs significantly decreased after large-scale supplemental folic acid intervention,while the incidence rate of CHD significantly increased.