Background: The aim of this study was to analyze the trends of multiple births at both national and provincial levels in Iran from 2014 to 2023.
Methods: Data on the number of live births and multiple births from 2014 to 2023 at national and provincial levels were obtained from the Iran’s Bureau of Vital Statistics. The multiple birth rate (MBR), defined as the number of live births from multiple births per 1,000 live births, was calculated annually. To examine temporal trends and detect significant changes in MBR over the study period, joinpoint regression analysis was performed. Annual percent change (APC) and average annual percent change (AAPC) were calculated for the entire period. 
Result: The national AAPC in the MBR was estimated at 2.38% (95%CI: 1.95 to 2.76) over the entire study period. A significant shift in trend was identified in 2020. Specifically, the APC from 2014 to 2020 was 0.24%. However, from 2020 to 2023, the APC markedly increased to 6.8%, reflecting a substantial rise in MBR during this latter period. Furthermore, the study findings demonstrated that nearly all provinces across the country have exhibited an upward trend in MBR in recent years.
Conclusion: The increasing trend of multiple births in Iran aligns with global patterns. Several factors may have contributed to this rise, including increased maternal age at childbirth, higher prevalence of infertility, expanded use of assisted reproductive technologies (ARTs), and shifts in population policies.