[1] Cent Finland Hlth Care Dist, Dept Obstet & Gynecol, Jyvaskyla, Finland
[2] Univ Turku, Dept Obstet & Gynecol, Fac Med, Turku, Finland
[3] Univ Turku, Dept Publ Hlth, Fac Med, Turku, Finland
[4] Kymsote, Dept Gynecol, Kotka, Finland
[5] Univ Turku, Dept Biostat, Turku, Finland
[6] Turku Univ Hosp TYKS, Dept Obstet & Gynecol, Turku, Finland
[7] Turku Univ Hosp TYKS, Clin Res Ctr, Turku, Finland