The risk of intrapartum cesarean delivery in advanced maternal age.

We aimed to investigate the association of advanced maternal age with intrapartum cesarean delivery and to assess its risk factors and perinatal outcomes. A retrospective cohort study of all women with singleton pregnancies who attempted a trial of labor (≥24 + 0 weeks of gestation) in a single center (2011-2017). The study population was stratified by parity (nulliparous or multiparous) and further sub-categorized into three cohorts: (1) women <35 years at birth (reference group), (2) women aged 35-40 years, and (3) women >40 years. Labor and delivery characteristics and neonatal outcomes were compared. Overall, 55,089 women were included: 39, 192 (71.1%) were under 35 years old, 15,90712,892 (28.923.4%) were 35-40 y and 3,015 (5.5%) were >40 y. For nulliparas, the rate of intrapartum Cesarean deliveries increased with maternal age and approached 25.3% in those >40 y as compared to 8.9% for those <35 y. The positive association between Cesarean section rates and maternal age extends beyond nulliparas and is also seen in multiparas, although to a smaller degree. After adjusting for confounders, maternal age was significantly and independently associated with intrapartum cesarean delivery in a dose-dependent manner in nulliparous women, [adjusted Odd Ratio (aOR) 1.56 (95% Confidence Interval (CI) 1.39-1.76) and 2.53 (2.07-3.09)] among women aged 35-40 y and >40 y, respectively. Maternal age was not significantly associated with adverse neonatal outcome. Advanced maternal age is an independent risk factor for intrapartum Cesarean delivery. Yet, the majority of older gravidae who attempt a trial of labor, even if nulliparous, deliver vaginally without an increase in adverse neonatal outcome.