Epidemiological trends of primary male infertility and secondary male infertility burden in BRICS from 1990 to 2021 and projections to 2035.
OBJECTIVE Male infertility is an important global reproductive health issue with implications for individuals, families, and population health. This study aimed to analyze the burden of primary male infertility (PMI) and secondary male infertility (SMI) in BRICS countries from 1990 to 2021 and project trends to 2035. METHODS PMI and SMI prevalence data were extracted from the Global Burden of Disease (GBD) 2021 database. Temporal trends from 1990 to 2021 were assessed using age-standardized prevalence rates (ASPRs) and estimated annual percentage changes (EAPCs). Future ASPR trends to 2035 were projected using a Bayesian age-period cohort model. RESULTS In 2021, Iran had the highest ASPR of PMI, whereas Russia had the highest ASPR of SMI. From 1990 to 2021, the EAPC of PMI was positive in China, India, Brazil, and Iran. The EAPC of SMI was positive in India, the United Arab Emirates, Brazil, and Egypt during the same period. South Africa and Ethiopia showed decreasing ASPR trends. Notably, in Egypt, the SMI-to-PMI ratio increased from 0.565 in 1990 to 1.112 in 2021. In 2021, the prevalence of PMI and SMI in BRICS countries varied across age groups. From 2022 to 2035, the projected ASPR of PMI decreased in all BRICS countries except Brazil and China, while the projected ASPR of SMI increased markedly in India and exceeded the global trend. CONCLUSION The burden and trends of PMI and SMI varied across BRICS countries. Iran had the highest ASPR of PMI, whereas Russia had the highest ASPR of SMI in 2021; China and India also showed substantial SMI burdens. The projected increase in SMI in India warrants particular attention. These findings may support targeted prevention, counseling, and treatment strategies for male infertility in BRICS countries.