Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing 100044, China;
Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing 100044, China;
Department of Obstetrics and Gynecology, Beijing Shunyi Women's and Children's Hospital, Beijing 101300, China;
Department of Obstetrics and Gynecology, Beijing Shunyi Women's and Children's Hospital, Beijing 101300, China;
Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing 100044, China;
Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing 100044, China;
Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing 100044, China;
Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing 100044, China;
Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing 100044, China;
Department of Obstetrics and Gynecology, Peking University People's Hospital, Beijing 100044, China;