Advanced Maternal Age Among Nulliparous at Term and Risk of Unscheduled Cesarean Delivery

Abstract

Background: With the rise in the number of women giving birth at an advanced age, the association between advanced maternal age and adverse obstetrical outcomes is a growing concern in developed countries. Despite the well-established link between advanced maternal age and pregnancy-related complications, there has been limited research examining the specific risks related to unscheduled cesarean delivery in nulliparas at term.

Objective: This study aimed to evaluate the risks associated with unscheduled cesarean delivery in nulliparas at ≥37 weeks of gestation, comparing the outcomes of younger patients with those aged ≥40 years.

Study design: This retrospective cohort study was conducted in a tertiary maternity hospital in Switzerland (high-income country). The study included nulliparas who delivered a live-born infant at ≥37 weeks between January 2015 and December 2019. We excluded pregnant women who had a planned cesarean delivery, were aged <18 years, multiparous, delivered before 37 weeks of gestation, or had pregnancies that ended in stillbirth. Participants were divided into 2 age groups: (1) ≥40 years and (2) <40 years. The primary outcome was the incidence of unscheduled cesarean delivery. Its association with advanced maternal age was evaluated after adjusting for confounding factors by multivariate logistic regression, expressed as an adjusted odds ratio. Secondary outcomes included pregnancy outcomes and neonatal outcomes.

Results: A total of 5211 patients were included: 173 in the ≥40-years (advanced maternal age) group and 5038 in the <40-years (non-advanced maternal age) group; 26.01% (95% confidence interval, 19.65-33.22; n=45) of women in the advanced maternal age group had an unscheduled cesarean delivery, whereas 15.26% (95% confidence interval, 14.28-16.29; n=769) of women in the non-advanced maternal age group underwent the procedure. Advanced maternal age was associated with unscheduled cesarean delivery, with an adjusted odds ratio of 1.51 (95% confidence interval, 1.06-2.17; P=.024). Among vaginal deliveries, assisted procedures were performed on 29.7% (95% confidence interval, 21.9-38.4; n=38) of advanced maternal age patients vs 20.1% (95% confidence interval, 18.9-21.3; n=856) of non-advanced maternal age patients. Postpartum blood loss >1000 mL occurred in 5.8% (95% confidence interval, 2.8-10.4; n=10) of advanced maternal age patients and 3.1% (95% confidence interval, 2.6-3.6; n=156) of non-advanced maternal age patients.

Conclusion: Advanced maternal age is associated with increased risk of unscheduled cesarean delivery among nulliparas. This provides healthcare professionals with confirmation that advanced age may represent an individual risk factor, suggesting that nulliparous patients aged over 40 years may benefit from improved information regarding the factors contributing to this pregnancy outcome.

Keywords: Advanced maternal age; cesarean delivery; delivery outcome; pregnancy outcome.