Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 51 5 2022 05 08 1057 1066 Hui Li Department of Medicine, Taixing People Hospital, Taizhou, Jiangsu, China Nawsherwan . Department of Preventive Medicine, School of Health Sciences, Wuhan University, Wuhan, Hubei, China Abbas Kkhan Department of Nutrition and Health Promotion, University of Home Economics, Lahore, Pakistan Ijaz Haq Department of Public Health and Nutrition, The University of Haripur, Khyber Pakhtunkhwa, Pakistan Shi Yuan Mei Department of Pediatrics, Taixing People Hospital, Taizhou, Jiangsu, China 2022 02 10 2022 05 08 Background: A tertiary-hospital-based retrospective study (2011-2019) was conducted to determine the mediating role of hypertensive disorders of pregnancy and abnormal placentations between advanced maternal age and adverse neonatal outcomes. Methods: Data from a tertiary-hospital-based retrospective study (n= 23051) was used and conducted regression-based mediation analysis to assess the mediating role of hypertensive disorders of pregnancy and abnormal placentation between the advanced maternal age and adverse neonatal outcomes. Results: After adjusting for confounding factors, the indirect effect of advanced maternal age on preterm births, perinatal mortality, and low birth weight mediated by hypertensive disorders of pregnancy was [aOR 4.95 (95% CI: 4.05, 5.85)], [aOR 2.82 (95% CI: 1.78, 3.86)], and [aOR 5.90 (95% CI: 4.93, 6.87)], respectively. The indirect effect of advanced maternal age on preterm births and low birth weight mediated by abnormal placentation was [aOR 6.83 (95% CI: 5.70, 7.97)] and [aOR 4.18 (95% CI: 3.26, 5.11)].  About, 23%, 37%, and 17% of the effect of advanced maternal age on preterm births, perinatal mortality, and low birth weight was mediated by hypertensive disorders of pregnancy, respectively. Furthermore, abnormal placentation mediates the association between advanced maternal age and preterm births by 18% and low birth weight by 23%.   Conclusion: Hypertensive disorders of pregnancy and abnormal placentation partially mediate the association between advanced maternal age and adverse neonatal outcomes.  https://ijph.tums.ac.ir/index.php/ijph/article/view/27822 https://ijph.tums.ac.ir/index.php/ijph/article/download/27822/7592