Too many embryos: a critical perspective on a global challenge.

Over the past decade, significant endeavors have been directed toward establishing an optimal oocyte number to maximize the chances for successful in vitro fertilization outcomes. The effectiveness of assisted reproductive technologies has greatly improved, and more good-quality embryos are being created in each cycle. However, many of these embryos remain unused. Notably, in Europe, approximately one-third of couples did not use their surplus cryopreserved embryos. Surplus embryos pose a challenge for patients and clinics. Embryo disposal practices are not the same all over the continent, with embryo donation and embryo discharge not allowed in several countries. In this scenario, limiting the number of surplus embryos by reducing the number of inseminated oocytes, according to couple clinical history, could be a strategy.