1. Department of Obstetrics and Gynecology, Qilu Hospital of Shandong University, Jinan, Shandong, China (mainland)
2. Department of Obstetrics and Gynecology, Yantai Affiliated Hospital of Binzhou Medical University, Yantai, Shandong, China (mainland)
3. Department of Obstetrics and Gynecology, First Peoples’ Hospital of Guiyang City, Guiyang, Guizhou, China (mainland)