The blood lead(PbB) levels of pregnant women and their babieswere followed up since the third month of pregnancy until their babies were 2 years old.

• 对妊娠3个月左右的孕妇开始进行追踪观察，并随访其子女至2岁。在此期间分别采集孕妇和婴幼儿的血样做血铅分析。