1. Key Laboratory of Reproduction Regulation of NPFPC, SIPPR, IRD; Fudan University; Shanghai 200032 China
2. Department of Fetal Medicine and Prenatal Diagnosis Center, Shanghai First Maternity and Infant Hospital; Tongji University School of Medicine; 200040 Shanghai China
3. Department of Women and Children's Health Care, Shanghai First Maternity and Infant Hospital; Tongji University School of Medicine; Shanghai 200040 China
4. Department of Clinical Epidemiology; Aarhus University Hospital; Olof Palmes Alle 43-45 DK-8200 Aarhus N Denmark
5. Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital; Shanghai Jiao Tong University School of Medicine; Shanghai China