Delivery outcome after trial of labor in nulliparous women 40 years or older—A nationwide population-based study

Abstract

Introduction: The number of women postponing childbirth until an advanced age is increasing. Our aim was to study the outcome of labor in nulliparous women ≥40 years, compared with women 25-29 years, after both spontaneous onset and induction of labor. Material and methods: The nationwide population-based Swedish Medical Birth Register was used to study the perinatal outcome in nulliparous women with a singleton, term (gestational weeks 37-44), live fetus in cephalic presentation and a planned vaginal delivery from 1992 to 2011. We included 7796 nulliparous women ≥40 years and 264 262 nulliparous women 25-29 years. Prevalence and risk of intrapartum cesarean section, operative vaginal delivery, obstetric anal sphincter injury and a 5-minute Apgar score <7 were calculated for women ≥40 years stratified for spontaneous onset and induction of labor, using women 25-29 years as the reference in both strata. Crude and adjusted odds ratios (aOR) were calculated by unconditional logistic regression and presented with 95% confidence intervals (CI). Results: Overall, 79% of women ≥40 years with a trial of labor reached a vaginal delivery. After spontaneous onset, intrapartum cesarean section was performed in 15.4% of women ≥40 years compared with 5.4% of women 25-29 years (aOR 3.07, 95% CI 2.81-3.35). Operative vaginal delivery was performed in 22.3% of women ≥40 years compared with 14.2% of women 25-29 years (aOR 1.71, 95% CI 1.59-1.85). After induction of labor, an intrapartum cesarean section was performed in 37.2% women ≥40 years compared with 20.2% women 25-29 years (aOR 2.51, 95% CI 2.24-2.81). Operative vaginal delivery was performed in 22.6% of women ≥40 years compared with 18.4% women 25-29 years (aOR 1.45, 95% CI 1.28-1.65). The risk of obstetric anal sphincter injury or a 5-minute Apgar score <7 was not increased in women ≥40 years, regardless of onset of labor. Conclusions: Trial of labor ended in vaginal delivery in 79% of nulliparous women ≥40 years. The risks of intrapartum cesarean section and operative vaginal delivery were higher in women ≥40 years compared with women 25-29 years, after both spontaneous onset and induction of labor. The risk of obstetric anal sphincter injury or a 5-minute Apgar score <7 was not increased.