Estrogen Administration in FET Cycles

Optimal Duration and Dosing

• Estrogen should be continued until target endometrial thickness of ≥7 mm is achieved, at which point progesterone supplementation begins, as recommended by the American Society for Reproductive Medicine 1
• After embryo transfer and positive pregnancy confirmation, estrogen should be continued at original doses for 3-4 weeks, then gradually reduced to complete discontinuation within 2 weeks, based on guidelines from the European Society of Human Reproduction and Embryology 2, 1

Critical Timing Considerations

• Progesterone supplementation should begin only after achieving endometrial thickness ≥7 mm, regardless of how many days of estrogen have been administered, according to the American College of Obstetricians and Gynecologists 1