Supplementary Material for: Global, regional and national temporal trends in prevalence for migraine in women of childbearing age: an updated age-period-cohort analysis based on Global Burden of Disease Study 2021

Introduction: To provide a comprehensive assessment of temporal trends in migraine prevalence among women of childbearing age (WCBA) at global, regional and national levels from 1992 to 2021, with particular emphasis on examining the associations between prevalence patterns and age, period and birth cohort effects across different sociodemographic index (SDI) regions. Methods: We conducted a secondary analysis of data from the Global Burden of Disease Study 2021. Migraine prevalence estimates and 95% uncertainty intervals (UI) for WCBA were extracted. An age-period-cohort model was employed to estimate the net drift (primary outcomes), local drift, age/period/cohort relative risks (secondary outcomes). Results: The global number of WCBA with migraine reached 493,937,856.01 (95% UI: 420,683,360.54 to 577,874,600.76) in 2021. The highest burden was found in India (95.7 million) and China (68.1 million), together accounting for substantial proportion of global prevalence. The global net drift showed minimal change 0.01% (95% CI: 0.00-0.02, p<0.01) per year, with variations across sociodemographic index (SDI) regions ranging from -0.03% per year, (95% CI: -0.04 to -0.02, p<0.01) in low-middle SDI regions to 0.16% (95% CI: 0.15-0.17, p<0.01) in middle-SDI regions. Local drift analysis reveals that migraine prevalence increases across young age groups (15-19 years) in high-SDI regions, while lower-SDI regions generally display stable rates. Globally, increases in migraine prevalence among young adults within WCBA are notably persistent. Across SDI regions, age effects follow similar patterns, with risk rising with age and peaking in the mid-reproductive years (ages 30-39). Over time, period risks and unfavorable trends across successive birth cohorts have intensified, particularly in high, high-middle, and middle-SDI regions. Conclusion: Although global migraine prevalence among WCBA remains stable, an unfavorable upward trend in younger age groups (15-19 years) in high, high-middle, and middle SDI regions, alongside worsening period/cohort risks, highlights current gaps in prevention and management. Improved strategies are expected to reduce risks for younger birth cohorts and all age groups over time.