Very Thin Endometria in the Late Proliferative Phase Is More Associated with Poor Pregnancy Rates Following Controlled Ovarian Hyperstimulation Than Graduated Estradiol Regimens Used for Frozen Embryo Transfer

Abstract

From the early days of IVF-ET thin endometria at the time of peak follicular maturation was negatively associated with pregnancy rates (PRs). Though improvement in IVF technology has produced “heartier” embryos there is still a negative association with thin endometria and pregnancy outcome but not as severe as before. One option for thin endometria is to freeze all embryos and transfer in a subsequent cycle using a graduated estrogen protocol which usually but not always improves the endometrial thickness.