方法：收集单胎活产分娩低体重儿胎盘50例为观察组，正常体重儿的胎盘50例为对照组；

Methods:100 infants, who were firstly normal delivery in hospital, were enrolled in the study. The 50 cases with low weight in test group, the 50 cases with normal weight as control.

youdao

方法：收集单胎活产分娩低体重儿胎盘50例为观察组，正常体重儿的胎盘50例为对照组；

Methods:100 infants, who were firstly normal delivery in hospital, were enrolled in the study. The 50 cases with low weight in test group, the 50 cases with normal weight as control.

youdao