1. Institute of Pediatrics, Guangzhou Women and Children's Medical Center, Guandong Provincial Clinical Research Center for Child Health , 9 Jinsui Rd, Guangzhou 510623 , China
2. Department of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong , 21 Sassoon Road, Pokfulam, Hong Kong S.A.R. , China
3. Shenzhen Key Laboratory of Fertility Regulation, The University of Hong Kong–Shenzhen Hospital , 1 Haiyuan 1st Road, Futian District, Shenzhen 518009 , China
4. Center of Reproduction and Prenatal Diagnosis, The University of Hong Kong–Shenzhen Hospital , 1 Haiyuan 1st Road, Futian District, Shenzhen 518009 , China