1. Johns Hopkins University School of Medicine; Division of Maternal Fetal Medicine, Department of Gynecology and Obstetrics; 600 N Wolfe Street Phipps 228 Baltimore Maryland USA 21287-1228
2. Faculty of Medicine, College of Health Sciences, Nnamdi Azikiwe University, Nnewi Campus; Effective Care Research Unit, Department of Obstetrics and Gynaecology; PMB 5001, Nnewi Anambra State Nigeria
3. University of Connecticut Health Center; Department of Infectious Diseases; 263 Farmington Avenue Farmington Connecticut USA 06053
4. Beijing University of Chinese Medicine Subsidiary Dongfang Hospital; Science of Education; No.6 District 1 Fangxingyuan, Fangzhuang, Fengtai District Beijing China 100078
5. Beijing University of Chinese Medicine Subsidiary Dongfang Hospital; No.6 District 1 Fangxingyuan, Fangzhuang, Fengtai District Beijing China 100078