Risk factors for preterm birth in advanced maternal age pregnancies: a retrospective study

To investigate the risk factors for preterm birth in women of advanced maternal age. A retrospective study of pregnant women with advanced maternal age who received regular prenatal examinations and delivered at Haidian District Maternal and Child Health Care Hospital between February 2020 and February 2025 was performed. Exposure information possibly related to preterm birth was collected via the hospital’s medical record system. Multivariate logistic regression analysis was used to investigate the risk factors for preterm birth in women of advanced maternal age. A total of 5,441 pregnant individuals of advanced maternal age were enrolled. Among these, 406 patients composed the preterm group. A control group (n = 812) was selected at a 1:2 ratio matched by delivery age, delivery date, and parity. Multivariate logistic regression analysis revealed that inadequate gestational weight gain, excessive gestational weight gain, history of preterm birth, history of early miscarriage, hypertensive disorders of pregnancy, placenta previa, premature rupture of membranes, white blood cell count and D-dimer level were risk factors for preterm birth in women with advanced maternal age (P < 0.05). Conversely, number of prenatal visits emerged as a protective factor against preterm birth (P < 0.05). Our findings underscore the multifactorial nature of risk factors for preterm birth in advanced maternal-age pregnancies. The implementation of enhanced health education, standardized antenatal care protocols, and rigorous comorbidity surveillance represents a critical pathway toward reducing PTB incidence in this vulnerable population.