Methods:Statistical analysis was done by modeling the data through COX regression model,which consisted of 1 075 perinatal born in Guangxi in the year 2000,317 cases with birth defects and 758 controls without birth defects.

• 方法 :采用 COX回归模型对广西 2 0 0 0年出生的围产儿 10 75例 (包括出生缺陷儿 317例和正常对照儿 75 8例 )进行干预模式拟合。