1. Department of Obstetrics and Gynecology, Peking University First Hospital, Beijing, China
2. Department of Obstetrics, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
3. Department of Obstetrics, Peking University Third Hospital, Beijing, China
4. Department of Endocrinology, Beijing Pinggu Hospital, Beijing, China
5. Department of Endocrinology, The 306 Hospital of PLA, Beijing, China
6. Department of Endocrinology, Chinese PLA General Hospital, Beijing, China
7. Department of Endocrinology, Peking University Peoples Hospital, Beijing, China