Maternal age and perinatal morbidity: a comparative cohort study including advanced maternal age and adolescent pregnancy

BACKGROUND: Maternal age at childbirth shows a bimodal risk distribution worldwide. While adolescent pregnancy remains common in many areas, the rate of advanced maternal age is rising in high-income countries. Both extremes are associated with adverse outcomes through different pathways. This study tests the hypothesis that adolescent (< 19 years) and older (> 35 years) mothers face higher obstetric and neonatal risks than young adults (19-35 years), regardless of key confounders. METHODS: A retrospective cohort study was conducted from 2019 to 2023 at a tertiary-care center. A total of 19,728 mother-neonate dyads were included and stratified by maternal age: adolescents (n = 1,570), young adults (n = 14,707), and older adults (n = 3,451). We analyzed maternal demographics, antenatal care, and maternal-neonatal outcomes. Multivariable logistic regression was adjusted for confounders, including socioeconomic status, parity, prenatal care, and comorbidities. Primary outcomes included mode of delivery, preterm birth, low birth weight, preeclampsia, and neonatal intensive care unit (NICU) admission. RESULTS: Older adult mothers showed the highest adjusted risks: preeclampsia (aOR = 3.15, 95% CI: 2.82-3.52), cesarean delivery (aOR = 1.89, 1.72-2.08), and preterm birth (aOR = 2.94, 2.68-3.22). Adolescent mothers had lower cesarean rates but significantly higher adjusted odds of low birth weight (aOR = 1.72, 1.45-2.04) and preterm birth (aOR = 1.48, 1.25-1.75). The likelihood of NICU admission increased for both groups. Socioeconomic disadvantage was most apparent among adolescents, while medical comorbidities characterized the older group. CONCLUSION: This study confirms a U-shaped risk curve, with both adolescent and advanced maternal ages remaining associated with increased risk after adjustment for measured confounders for adverse pregnancy outcomes. The findings highlight the need for specific, age-tailored clinical and public health strategies: targeted social support and early prenatal care for adolescents, and careful monitoring and management of medical comorbidities for older mothers.