[1] Maxima MC, Dept Obstet & Gynaecol, POB 7777, NL-5500 MB Veldhoven, Netherlands
[2] Eindhoven MedTech Innovat Ctr eMTIC, Eindhoven, Netherlands
[3] Eindhoven Univ Technol, Dept Elect Engn, POB 513, NL-5600 MB Eindhoven, Netherlands
[4] Harvard Med Sch, Brigham & Womens Hosp, Dept Obstet & Gynaecol, Div Maternal Fetal Med, 75 Francis St, Boston, MA 02115 USA