1. From the Department of Obstetrics and Gynaecology, University of British Columbia, Vancouver, Canada (J.A.H.)
2. Clinical Epidemiology Unit, Department of Medicine, Solna (O.S., S.C., K.W., K.J.)
3. Division of Obstetrics and Gynaecology, Department of Women’s and Children’s Health (O.S.)
4. Karolinska Institutet, Stockholm, Sweden; Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, PA (L.M.B.)
5. Department of Women’s and Children’s Health, Uppsala University, Sweden (A.-K.W.).