Annual Trend in Zygotic Twinning Rates and their Association with Maternal Age in Japan, 1999-2008

Yoko Imaizumi^* and Kazuo Hayakawa

Department of Health Sciences, Graduate School of Medicine, Osaka University, Suita City, Osaka, Japan

^*Corresponding Author: Yoko Imaizumi, Professor, Department of Health Sciences, Graduate School of Medicine, Osaka University, A-1302, Kokubo 120-55, Akashi City, Hyogo Prefecture 673-0005, Japan, Tel: +81-78-928-6027 Email: