Affiliation: | 1.Department of Obstetrics and Gynecology, Fengxian Hospital, Southern Medical University, Shanghai 201499, P. R. China;2.Obstetrics and Gynecology Hospital, Fudan University, Shanghai 200011, P. R. China;3.Changzhou Maternal And Child Health Care Hospital, 213003 Jiangsu, P. R. China;4.Shanghai Jiading Maternal and Child Health Care Hospital, Shanghai 201899, P. R. China |