1. Dept. of Obstetrics and Gynecology, Roskilde Hospital, Roskilde, Denmark
2. Dept. of Obstetrics, Rigshospitalet, Copenhagen, Denmark
3. Yale Women and Children's Center for Blood Disorders, Dept. of Obstetrics, Gynecology, and Reproductive Medicine, Yale University School of Medicine, New Haven, CT, USA
4. Dept. of Community Health/Epidemiology, Brown University School of Medicine, Providence, RI, USA