Global Trends, Regional and National Disparities in Infertility Attributable to Sexually Transmitted Infections, Excluding HIV: A Comprehensive Analysis from 1990 to 2021, and Predictions to 2035

Background: In 2021, approximately 18.41 million women globally experienced infertility due to sexually transmitted infections (STIs), excluding human immunodeficiency virus (HIV) infections. In this study, STIs refer specifically to non-HIV infections. Although the global prevalence of STIs is well-documented, their contribution to infertility across diverse socioeconomic contexts remains understudied. This study analysed the burden of infertility caused by STIs among women of reproductive age across 204 countries and regions between 1990 and 2021, with projections extending to 2035. Methods: Data from the Global Burden of Disease (GBD) 2021 database were used to assess the prevalence and years lived with disability (YLDs) associated with STI-related infertility, among women aged 15–49. The number of cases, incidence rate per 100,000 people, and annual percentage change (AAPC) were assessed at global, regional, and national levels. A Bayesian age-period-cohort model was employed to predict the age-standardised prevalence rate (ASPR) from 2022 to 2035. Results: The number of women aged 15–49 years with infertility due to STIs increased from 10.71 million in 1990 to 18.41 million in 2021, reflecting a significant upward trend globally. In 2021, the prevalence corresponded to 455 cases per 100,000 people. The age-standardised YLD rate was 2.55 years per 100,000 people. Secondary infertility exhibited a faster growth rate compared to primary infertility. Although the annual growth rate of the disease burden in regions with a low-socio-demographic index (SDI) is decreasing, it remains significantly higher than in regions with other SDI categories. Medium-SDI regions demonstrated the fastest growth trend. Among individual countries, Cameroon had the highest national ASPR and age-standardised YLD rate of infertility. A negative correlation was observed between disease burden estimates and SDI levels, indicating that countries with lower SDI values bear a disproportionate burden. However, projections suggest a decline in its prevalence globally and across most regions by 2035. Conclusions: These findings highlight the urgent need for targeted, age-specific interventions and the development of equitable health systems to reduce the prevalence of STI-related infertility. Implementing effective hygiene practices, along with robust prevention and management strategies, is crucial in alleviating the burden and improving reproductive health outcomes worldwide.