1. Department of Public Health Graduate School of Medicine The University of Tokyo Bunkyo‐ku Tokyo Japan
2. Department of Obstetrics and Gynecology Graduate School of Medicine The University of Tokyo Bunkyo‐ku Tokyo Japan
3. Department of Economics University of Arizona Tucson Arizona USA
4. Hematology Division Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital Bunkyo‐ku Tokyo Japan
5. Department of Obstetrics and Gynecology School of Medicine Nihon University Itabashi‐ku Tokyo Japan