1. Graduate School, Southern Medical University, Guangzhou, P.R. China.
2. Key Laboratory for Reproduction and Genetics of Guangdong Higher Education Institutes, Key Laboratory for Major Obstetric Diseases of Guangdong Province, Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, P.R. China.
3. Shenzhen Maternity and Child Healthcare Hospital, Shenzhen, P.R. China.