[1] New Croft Ctr, Sexual Hlth Serv, Newcastle Upon Tyne NE1 6ND, Tyne & Wear, England
[2] Univ Estadual Campinas, UNICAMP, Sch Med, Dept Obstet & Gynaecol,Human Reprod Unit, BR-13081970 Campinas, SP, Brazil
[3] Natl Inst Hormones & Women Hlth, BR-13081970 Campinas, SP, Brazil
[4] Univ Edinburgh, Queens Med Res Inst, Div Reprod & Dev Sci, Edinburgh EH16 4TJ, Midlothian, Scotland
[5] Univ Calif San Francisco, San Francisco Gen Hosp, Bixby Ctr Global Reprod Hlth, San Francisco, CA 94941 USA
[6] Univ Sydney, Queen Elizabeth II Res Inst Mothers & Infants, Dept Obstet & Gynaecol, Sydney, NSW 2006, Australia