1. NHC Key Laboratory of Male Reproduction and Genetics, Guangzhou, Guangdong 510600, China
2. Family Planning Research Institute of Guangdong, Guangzhou, Guangdong 510600, China
3. Department of Epidemiology, Medical School of Jinan University, Guangzhou, Guangdong 510632, China
4. Women and Children’s Hospital of Guangdong Province, Guangzhou, Guangdong 511400, China