The aim of this multicenter retrospective cohort study was to examine the impact of maternal age on perinatal outcomes in multiparas, stratified according to maternal age in one- and two-year increments. The analysis involved 302,484 multiparas who delivered between the years 2003 and 2021 in four university-affiliated obstetrics departments. Maternal age was considered both as a continuous variable and in two-year intervals, as compared with a comparison group of parturients aged 25-30 years. The study focused on cesarean delivery and neonatal intensive care unit (NICU) admission as primary outcomes. The findings revealed that cesarean delivery rates increased as maternal age advanced, with rates ranging from 6.7% among 25-30 year olds, rising continuously from 13.5% to 19.9% between the age strata of 31 and 42, to exceeding 20% among those aged ≥ 43 years (p < 0.01 for each stratum when compared to 25-30 year old group). Similarly, NICU admission rates rose from 2.7% in the comparison group to 6% in parturients aged 45-46 years (p < 0.01 for each stratum when compared to 25-30 year old group). The study highlights the association between incrementally advanced maternal age and increased rates of maternal and neonatal complications, necessitating global awareness of these implications for family planning decisions and maternal care.
Keywords: NICU admission; advanced maternal age; cesarean delivery; mechanical ventilation; neonatal asphyxia; perinatal outcomes; preterm delivery.