1. Obstetrics and Gynecology Department, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
2. School of Public Health, Epidemiology, Biostatistics and Clinical Research Centre, Université Libre de Bruxelles (ULB), Brussels 1070, Belgium
3. Hematology Department, The Affiliated Hospital of Chengde Medical College, Chengde 067000, China