1. Norwegian National Advisory Unit on Women’s Health and
2. Cancer Registry of Norway, Institute of Population-Based Cancer Research, Oslo, Norway; and
3. Section for Reproductive Medicine, Department of Gynecology, Oslo University Hospital, Rikshospitalet, Oslo, Norway;
4. Division of Cancer Epidemiology & Genetics, Hormonal and Reproductive Epidemiology Branch, National Cancer Institute, Bethesda, Maryland