A group of researchers from the Reproductive Medicine Unit of our centre have conducted a large study to assess whether the presence of high levels of progesterone in patients on hormone replacement therapy could have a negative impact on reproductive outcomes in frozen embryo transfers (FET).

The study included a total of 3,183 frozen embryo transfer (FET) cycles in patients on hormone replacement therapy between March 2009 and December 2020. A total of 1,360 cycles were frozen homologous embryo transfers (hom-FET), 1,024 were frozen euploid embryo transfers (eu-FET) after preimplantation genetic testing for aneuploidy, and 799 cycles were frozen heterologous embryo transfers (het-FET). All patients had adequate serum progesterone levels prior to the procedure.

According to the results, no differences in live birth rates were found between patients with high progesterone levels ( >p90 and >p95) versus the rest of the patients. Furthermore, the results were similar for the different types of FET analysed (hom-FET, eu-FET and het-FET).

The authors concluded that elevated serum progesterone levels before a frozen embryo transfer do not negatively impact reproductive outcomes as long as the patient has an adequate minimum level of progesterone the day before or on the day of the transfer (10.6 ng/mL).