Affiliation: | a National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Peking Union Medical College, Tsinghua University, 5 Dong Dan San Tiao, Beijing 100005, China b National Research Institute for Family Planning Beijing, WHO Collaboration Center of Human Reproduction, 12 Da Hui Si, Hai Dian, Beijing 100081, China c Center for Biomedical Research, Population Council, 1230 York Avenue, New York, NY 10021, USA |