[1] Univ Hosp Leuven, Dept Obstet & Gynaecol, Herestr 49, B-3000 Leuven, Belgium
[2] Katholieke Univ Leuven, Dept Dev & Regenerat Cluster Woman & Child, Biomed Sci, Leuven, Belgium
[3] Katholieke Univ Leuven, Fac Med, Leuven, Belgium
[4] Univ Coll London Hosp, Inst Womens Hlth, London, England