1. Department of Obstetrics and Gynecology, Osaka Medical College, 2-7, Daigaku-chyo, Takatsuki, Osaka 569-8686, Japan
2. Department of Perinatology and Gynecology, National Cerebral and Cardiovascular Center, 6-1, Kishibe-shimmachi, Suita, Osaka 565-8565, Japan
3. Department of Perinatology and Gynecology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
4. Center for Cerebral and Cardiovascular Disease Information, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
5. Department of Preventive Medicine, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan
6. Department of Anesthesiology, National Cerebral and Cardiovascular Center, Suita, Osaka, Japan