Impact of the recommendation for embryo transfer limitation on multiple pregnancy: A population-based study in Japan

Limitations on the number of embryos transferred have been recommended worldwide to reduce the number of medically assisted multiple births. Our aim was to evaluate the impact of this recommendation for embryo transfer limitation on perinatal outcomes of multiple births.

A retrospective and population-based study compared all multiple births in Shiga prefecture of Japan in 2014-2015 (2015 group) with those in 2007-2008 (2008 group). The perinatal background and neonatal outcomes of multiple births were compared.

The number of multiple pregnancies in the 2015 group (n = 251) was almost the same as in the 2008 group (n = 245). The proportion of multiple pregnancies conceived through assisted reproductive technology significantly decreased to 23% in the 2015 group compared to 31% in the 2008 group. In contrast, the rate of ovulation induction significantly increased to 24% in the 2015 group from 15% in the 2008 group. There was no significant difference in the outcome of multiple-birth infants between the two groups.

The method of conception in multiple pregnancies markedly shifted from in vitro fertilization to non-in vitro fertilization after the issuance of a recommendation for limits on embryo transfer. It should be necessary for the assessment of the impact of this recommendation to monitor closely multiple pregnancies via non-in vitro fertilization as well as via in vitro fertilization.