1. Reproductive Center Laboratory, Ninghai County Maternal and Child Health Hospital, Ningbo, Zhejiang, PR China
2. Department of Maternal Health Care, Shiyan Maternal and Child Health Hospital, Shiyan, Hubei, PR China
3. Department of Obstetrics, Huanggang Central Hospital, Huanggang, Hubei, PR China
4. Department of Obstetrics and Gynecology, Huangshi Central Hospital, Affiliated Hospital of Hubei Polytechnic University, Edong Healthcare Group, Huangshi, Hubei, PR China