Japan recorded a sharp rise in multiple pregnancies linked to assisted reproductive technology (ART) in 2023, reaching a record 4,354 cases, according to a recent study.
The increase came one year after fertility treatments were included under Japan’s public health insurance system, reported Japan Today.
The figure marked a 36% increase from 2022, with researchers suggesting that insurance design may be influencing clinical decisions. In particular, the study noted that some patients may be opting for multiple embryo transfers to maximise pregnancy success within the limited number of cycles covered under the national insurance scheme.
Japan’s public insurance system covers up to six embryo transfer attempts for women under 40 at the start of treatment and up to three attempts for those aged 40 to 42. Researchers said this structure may inadvertently encourage higher-risk approaches in some cases, despite long-standing medical guidance recommending single embryo transfer in principle.
The Japan Society of Obstetrics and Gynecology has advised that only one embryo should generally be transferred at a time to reduce the risk of multiple pregnancies, which carry higher maternal and neonatal health risks.
However, the multiple pregnancy rate rose to 3.8% in 2023, reversing a long-term decline that had stabilised at around 3% since 2014.
Most cases involved twins, although the study also recorded 69 triplet pregnancies and six cases of quadruplets. The researchers noted an increase in the transfer of two or more embryos, particularly among patients aged 41 and above.
Experts involved in the study said the findings raise questions about how insurance coverage structures may be shaping clinical behaviour.
The findings come as Japan continues to expand public insurance support for fertility treatment, with total assisted reproductive technology procedures also rising alongside coverage expansion.