BACKGROUND: The age at first delivery is rising leading to an increasing proportion of women with advanced maternal age (AMA) which is defined as greater than or equal to 35 years at time of delivery. Previous studies have associated AMA with adverse maternal and neonatal outcomes leading to an arbitrary increased rate of cesarean sections amongst AMA women without clear medical indications. OBJECTIVE: To determine the associations between AMA and adverse maternal and neonatal outcomes in nulliparous women in a large cohort. METHODS: Our retrospective cohort study looked at 44,295 nulliparous women (39,496 <
35years and 4,799 ≥ 35years) with term singleton gestation who delivered in the obstetrical units of Hadassah Medical Organization in Jerusalem, Israel, between 2003 and 2017. Data on maternal characteristics and outcomes, and neonatal outcomes were extracted from the electronic database. Outcomes were compared between women with AMA and women <
35 using Chi square, Fisher exact and t-tests. Multivariable logistic regressions estimated odds ratios (OR) for outcomes, controlling for confounders. We reported two-sided p-values, adjusted odds ratio (aOR), and 95% confidence intervals (CI). RESULTS: Women with AMA were more likely to have c-sections compared to women <
35 years in the whole study population (aOR:2.29, 95% CI: 2.13-2.47, p <
0.0001) including women having inductions (aOR:1.38, 95% CI:1.25-1.53, p <
0.0001). Self-requested c-sections were significantly higher among women with AMA (16.8% vs. 2.8%, OR:6.9, 95% CI:5.5-8.8). AMA did not increase the risk of postpartum hemorrhage (aOR: 0.82, 95% CI: 0.72-0.94) and decreased likelihood of instrumental delivery (aOR:0.81, 95% CI: 0.73-0.89, p <
0.0001). Fewer women with AMA had 3rd- and 4th-degree tears (0.35% for ≥ 35years vs. 0.71% for <
35 years, RR:0.50, 95% CI:0.29-0.87, p = 0.012). Women with AMA were more than three times likely to have an intrauterine fetal demise (RR:3.53, 95% CI:2.54-4.90, p <
0.0001), but were not more likely to have low neonatal 5-minute APGAR scores (RR:0.79, 95% CI: 0.43-1.46, p value:0.44) or NICU admissions (RR:0.84, 95% CI: 0.61-1.17, p = 0.30). CONCLUSIONS: Management of nulliparous AMA patients should be based on obstetric considerations and not solely on AMA status. Shared decision making is preferred to reduce the risks associated with AMA.