The study was conducted from January until June 2007 in the Department of Gynaecology and Obstetrics at Kalmar County Hospital, Sweden. The consultant-led delivery suite has approximately 1400 deliveries annually. After approval by the local ethical committee, women were informed about the study during antenatal classes. All women at term (37 full gestational weeks) were eligible with patient refusal as the only exclusion criterion. During the study period, 554 eligible women were delivered, of these 46 declined study participation, and 213 women were not included as they were uninformed or very near delivery. To complete the control group of women delivered by elective caesarean section, an additional 13 women were enrolled before study completion in September 2007. After written informed consent, 308 women were included in the study, but 21 women were later excluded as blood sample analysis were incomplete, leaving 287 participants in the study groups (125 nulliparas and 162 multiparas).