Zhejiang University - Department of Obstetrics and Gynecology, Zhejiang University, Zhejiang University, Zhejiang University, Zhejiang University, Zhejiang University, Quzhou Maternal and Child Health Hospital, Zhejiang University, Zhejiang University, Zhejiang University, Zhejiang University, Zhejiang University and Zhejiang University - Department of Obstetrics and Gynecology