Hypertension identified in early adulthood as an endocrine-vascular risk factor for uterine fibroids in reproductive-age women: a nationwide cohort study.

INTRODUCTION: The association between hypertension identified in early adulthood and uterine fibroid development in young women remains poorly understood. Therefore, we aimed to evaluate the association between hypertension identified in early adulthood and uterine fibroid development in reproductive-age women. METHODS: In this nationwide population-based cohort study, we used data from the Korean National Health Insurance Service, health screening and claims database. A total of 2,558,659 women aged 20-39 years without a prior diagnosis of uterine fibroids were enrolled between 2009-2012 and followed for a mean duration of 11.54 years until December 31, 2023. The main outcome measures were incident uterine fibroids and adjusted hazard ratios (HRs) according to blood pressure categories. Blood pressure was categorized as normotension, elevated/stage 1 hypertension, stage 2 hypertension, or treated hypertension according to national guidelines. Incident uterine fibroids were identified using International Classification of Disease 10th revision code D25. Cox proportional hazards models were used to estimate HRs and 95% confidence intervals (CIs), adjusting for demographic factors, lifestyle behaviors, body mass index (BMI), metabolic comorbidities, and healthcare utilization. RESULTS: During follow-up, 373,379 women (14.59%) developed uterine fibroids. Compared with normotensive women, elevated/stage 1 hypertension (adjusted HR 1.04; 95% CI 1.03-1.05) and stage 2 hypertension (adjusted HR 1.06; 95% CI 1.04-1.09) were associated with a progressively increased risk of incident uterine fibroids (all P < 0.001). Women receiving antihypertensive medication exhibited the highest risk (adjusted HR 1.10; 95% CI 1.06-1.14; P < 0.001). These associations were stronger among women with BMI < 25 kg/m² compared with those with BMI ≥ 25 kg/m² (P for interaction < 0.0001), and among women with waist circumference < 85 cm compared with those with waist circumference ≥ 85 cm (P for interaction = 0.0005). No association was observed according to antihypertensive medication class. CONCLUSIONS: Hypertension identified in early adulthood was independently and progressively associated with incident uterine fibroids in reproductive-age women. These findings suggest that blood pressure dysregulation during early adulthood may be relevant to uterine fibroid risk in young women.