| Affiliation: | 1. Department of Ultrasound, Maternal and Child Healthcare Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, China;2. Department of Ultrasound, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China;3. Department of Ultrasound, Hubei Provincial Maternal and Child Healthcare Hospital, Wuhan, Hubei, China;4. Department of Ultrasound, Sichuan Provincial Maternal and Child Healthcare Hospital, Chengdu, Sichuan, China;5. National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China;6. Department of Obstetrics & Gynecology, Fujian Provincial Maternal and Child Healthcare Hospital, Fuzhou, Fujian, China |
