大橋 麻衣

AIM: To evaluate the impact of health insurance coverage for assisted reproductive technology (ART), introduced in Japan in April 2022, on the number of multiple embryo transfers (METs) and multiple pregnancies. METHODS: We analyzed Japanese ART registry data from over 600 registered ART facilities, comparing the rates and numbers of multiple pregnancies in 2022 with those in previous years. Furthermore, age-specific MET rates and proportions of blastocyst transfers in METs were examined separately for fresh and frozen-thawed embryo transfers. RESULTS: In 2022, 3209 multiple pregnancies were reported, showing an increasing trend and a level equivalent to that in 2007, before single embryo transfer was recommended in the Japan Society for Obstetrics and Gynecology guidelines. For all embryo transfers, the MET rate was significantly lower in 2022 than in 2021, decreasing from 15.4% to 15.0% (p < 0.001), resulting in a similar rate of multiple pregnancies (2.98% vs. 3.05%; p = 0.17). Age-specific MET rates demonstrated a similar increasing trend with age between 2021 and 2022. However, the blastocyst utilization rate in METs was significantly higher in 2022 than in 2021 across almost all age strata in frozen-thawed embryo transfers. CONCLUSIONS: In 2022, the MET rate significantly decreased from 2021, whereas the multiple pregnancy rate remained similar. However, the absolute number of multiple pregnancies increased to the level before the single embryo transfer guideline, and the proportion of blastocyst transfers in MET also increased. Continuous monitoring is necessary to capture trends in the number of multiple pregnancies following ART in Japan.