Methods
A prospective observational study called `the dysfunctional labour study´ was performed at Soder Hospital
Stockholm, Sweden between April 2010 and January 2012. Healthy, Swedish-speaking, nulliparous women, with a singleton pregnancy and a gestational age between 37–42 weeks, were asked to participate. A number of criteria for inclusion were formulated: labour should have started spontaneously, the foetus should be in a cephalic presentation, the cervical dilation should be at least 3 cm and regular, painful contractions should be present.