Impact of maternal age on intrapartum caesarean delivery rate in nulliparas with spontaneous labour

The advanced maternal age rate increases in developed countries. Older women have more pre-existing condition than youngest women and develop more frequently obstetrical pathologies responsible for a higher rate of caesarean delivery before labour and labour induction. For aged nulliparous without pathology who experience spontaneous labour, there is few data on the mode of delivery and on physiological labour according to maternal age. To compare the intrapartum caesarean delivery rate according to maternal age, for nulliparous with planned vaginal delivery and spontaneous labour at term. Retrospective cohort in a single academic institution between January 2000 and June 2017. All nulliparous women with planned vaginal delivery with live singleton in cephalic presentation at and after 37 weeks of gestation with spontaneous labour were included (n = 10,611). Two groups were compared: nulliparous women aged 20–34 and nulliparous women aged 35 and over. The main outcome was the intrapartum caesarean delivery rate. A subgroup analysis was performed for nulliparous with more advanced maternal age defined as women over 40. Among the 10,611 women included in this analysis, 8,993 (84.8%) were aged 20–34 and 1,618 (15.2%) were aged over 35. From the latter 367 (22.7%) were over 40 years old. The intrapartum caesarean delivery rate was similar between women aged between 20 and 34 and women aged over 35 (10.8% compared to 8.8%; cOR 0.91, 95% CI 0.76–1.08; aOR 0.91, 95% CI 0.76–1.09). The indications of caesarean were similar in both groups. No differences were found between both groups for mean labour duration (430.9 min for the [20–34] years group compared to 428.0 min for the over 35 years group, p = 0.654). The subgroup analysis performed on nulliparous with more advanced maternal age yielded similar results. For nulliparous at term in spontaneous labour, an advanced maternal age was not associated with an increased intrapartum caesarean delivery rate.