1. The Institute of Traditional Chinese Medicine of Hebei University Health Science Centre, Baoding, Hebei 071002, P.R. China
2. The Medical Comprehensive Laboratory Center of Hebei University Health Science Centre, Baoding, Hebei 071002, P.R. China
3. The Centre for Reproductive Medicine of Peking University Third Hospital, Beijing 100191, P.R. China
4. Key Laboratory of Family Planning and Healthy Birth, National Health and Family Planning Commission Hebei Research Institute for Family Planning, Shijiazhuang, Hebei 050071, P.R. China