1. Department of Obstetrics and Gynecology; Xinhua Hospital; Shanghai Jiao Tong University School of Medicine; Shanghai China
2. Department of Dermatology; Xiangya Hospital; Central South University; Changsha China
3. Eunice Kennedy Shriver National Institute of Child Health and Human Development; Bethesda MD USA
4. United Nations Development Programme/United Nations Population Fund/United Nations International Children's Emergency Fund/WHO/World Bank Special Programme of Research; Development and Research Training in Human Reproduction; Department of Reproductive Health and Research; WHO; Geneva Switzerland
5. Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health; Xinhua Hospital; Shanghai Jiao Tong University School of Medicine; Shanghai China