[1] Univ Med Ctr Rotterdam, Erasmus MC, Dept Obstet & Gynaecol, Rotterdam, GD, Netherlands
[2] Univ Med Ctr Rotterdam, Erasmus MC Sophia Childrens Hosp, Dept Paediat, Div Neonatol, Rotterdam, Netherlands
[3] Univ Med Ctr Rotterdam, Erasmus MC, Dept Publ Hlth, Rotterdam, Netherlands
[4] Univ Med Ctr, Erasmus MC, Dept Obstet & Gynaecol, POB 2040, NL-3000 Rotterdam, Netherlands