Association Between Obesity Severity and Peripartum Maternal and Neonatal Outcomes Among Advanced Maternal Age Pregnant Women.

Background Obesity and advanced maternal age are both associated with adverse maternal and neonatal outcomes. However, the effect of increasing obesity severity within an advanced maternal age population remains insufficiently characterized, particularly in regional cohorts. Objective The objective of this study is to investigate the association between obesity severity and peripartum maternal and neonatal outcomes among pregnant women of advanced maternal age. Methods This retrospective cohort study was conducted at the Specialized Hospital for Women's Health, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia. Medical records of pregnant women aged 35 years or older with obesity who delivered between 2022 and 2025 were reviewed using the BESTCare database. Women were classified into obesity Class I, Class II, and Class III according to body mass index. Maternal, obstetric, and neonatal outcomes were compared across obesity classes using appropriate statistical tests. Results A total of 1162 women were included, of whom 478 (41.1%) had Class I obesity, 424 (36.5%) had Class II obesity, and 260 (22.4%) had Class III obesity. Mode of delivery differed significantly across obesity classes (P=.017), with the highest cesarean delivery rate observed in Class III obesity. Women with Class III obesity also had the highest median birth weight, and birth weight distribution differed significantly across groups (P<.001). High birth weight was more frequent and low birth weight was less frequent among women with Class III obesity. Diabetes differed significantly across obesity classes, whereas hypertension and deep vein thrombosis did not. No significant differences were observed across obesity classes in perineal tears, episiotomy, postpartum hemorrhage, gestational age, Apgar scores, neonatal intensive care unit admission, or birth injury. Intrauterine fetal death showed a statistically significant difference across groups, although event numbers were small. Conclusion Among pregnant women of advanced maternal age, increasing obesity severity, particularly Class III obesity, was associated with a higher cesarean delivery rate and higher birth weight. Most other maternal and neonatal outcomes were similar across obesity classes. These findings highlight the clinical importance of obesity class stratification in advanced maternal age pregnancies and may help inform antenatal counseling and delivery planning in high-risk obstetric populations.