1 Department of Obstetrics and Gynecology, Peking University First Hospital, Xi'an Men St. 1, Beijing 100034, China; Beijing Key Laboratory of Maternal Fetal Medicine of Gestational Diabetes Mellitus, Beijing, China.
2 Department of Obstetrics and Gynecology, Peking University First Hospital, Xi'an Men St. 1, Beijing 100034, China; Beijing Key Laboratory of Maternal Fetal Medicine of Gestational Diabetes Mellitus, Beijing, China. Electronic address: yanghuixia@bjmu.edu.cn.