Progesterone-modified Natural Cycle for FET

A novel endometrial preparation protocol that optimizes the natural cycle, whereby as long as the thickness of the endometrium is suitable for embryo transfer, vaginal progesterone can be used to transform the endometrium before ovulation and subsequently FET.

A traditional endometrial preparation protocol is used for FET, which involves using fixed or flexible exogenous estradiol for artificial cycles. This protocol typically involves starting exogenous estradiol on day 3 or 4 of the cycle, continuing for 7-10 days, and then discontinuing. Upon determining that the endometrial thickness meets the standard, progesterone conversion of the endometrium can be performed.