Positive and Negative Aspects of Public Insurance Coverage on ART With Respect to Multiple Gestation in Japan.

Purpose: This study examined whether the application of public insurance on assisted reproductive technology in Japan was associated with changes in the incidence of multiple blastocyst transfer (MBT) and subsequent multiple pregnancies (MP). Methods: A total of 2764 blastocyst transfer cycles performed at IVF Osaka Clinic from the pre-insurance period (January 2020-March 2022) were retrospectively compared with 4,326 cycles from the insurance period (April 2022-February 2025). MP was defined as two or more gestational sacs. Results: Baseline analysis showed that patients' age after insurance coverage was significantly younger with fewer previous ET attempts than pre-insurance. MBT rose from 5.8% pre-insurance to 20.1% under insurance, and MP increased from 0.7% to 2.6%, simultaneously. Insurance coverage was independently associated with a higher likelihood of MBT, an association most pronounced in the older age cohort. MBT exhibited the highest risk profile for MP. Significant upward trends in MBT and MP were observed as patients approached their final insured cycles. Conclusions: Findings suggest a correlation between insured cycle limits and clinical practice toward prioritizing per-cycle success. Although alleviating financial burden, the policy appears to be associated with increased MBT and MP, making it necessary to deliberate its impact on maternal and neonatal safety.