1. Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Guangzhou Medical University, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, Guangzhou, China
2. Department of Obstetrics and Gynecology, Sun Yat-Sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
3. Department of Obstetrics, Foshan Women and Children Hospital, Foshan, China
4. Department of Medical Affairs Section, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
5. Department of Obstetrics, Dongguan Songshan Lake Central Hospital, Dongguan, China
6. Department of Obstetrics, Maternal and Child Health Hospital of Guangdong, Guangzhou, China.