[1] Reprod BioMed Online, Cambridge CB3 8DB, England
[2] Yale Univ, Fertil Ctr, New Haven, CT 06511 USA
[3] Royal Hosp Women, Reprod Serv Melbourne IVF, Carlton, Vic 3053, Australia
[4] Univ Melbourne, Dept Obstet & Gynaecol, Parkville, Vic 3052, Australia
[5] NCI, Hormonal & Reprod Epidemiol Branch, Rockville, MD 20852 USA