1 Department of Obstetrics and Gynaecology, Amsterdam University Medical Centre, Amsterdam, Netherlands; Academie Verloskunde-Amsterdam en Groningen, Amsterdam 1059GL, Netherlands. Electronic address: s.l.m.logtenberg@gmail.com.
2 Department of Obstetrics and Gynaecology, Monash University, Melbourne, Australia.
3 Department of Midwifery Science, Amsterdam UMC Vrije Universiteit, Amsterdam, Netherlands; Maxima Medical Centre, Veldhoven, Netherlands.