Follicular Phase Serum Hormone Concentrations in Cryopreserved Embryo Transfer Cycles: Is There a Minimum Threshold Level for a Successful Pregnancy?

Abstract

Background: Cryopreservation of supernumerary embryos has been successful for almost three decades. Thawed embryos can be transferred in subsequent artificial or natural cycle. In a study by Venners et al, higher follicular phase estrogen metabolites concentration was associated with higher probability of achieving a clinical pregnancy in normally cycling women (Venners, Hum Reprod, 2006; 2272-2280). This interesting finding may apply to cryopreserved embryo transfer cycles since the follicular phase in such cycles is relatively similar to the follicular phase in normal menstrual cycles.