Why is micronised progesterone used in frozen embryo transfer?

In a programmed frozen transfer cycle, the clinic may use hormones to prepare the lining before thawed embryo transfer. Progesterone helps the lining become receptive and maintains it during the early stage after transfer. The schedule is tied to the embryo's development and the clinic's timing, so starting or stopping it independently can disrupt the plan. Some people notice discharge, breast tenderness, bloating or tiredness.

Follow the exact instructions for the prescribed route, timing and dose. Ask before substituting a different progesterone product or changing use after spotting. Continue until your fertility team gives a result-based plan, and attend the arranged pregnancy test. Tell the clinic about severe pain, heavy bleeding, medicines and allergies.

Call the fertility clinic urgently for heavy bleeding, severe one-sided pelvic pain, fainting, pronounced abdominal swelling or breathlessness. Emergency care is needed for collapse or severe breathing difficulty. These symptoms require assessment and are not explained away by progesterone alone.

Ask whether your cycle is hormone-prepared, why progesterone is needed, how long it is planned, what a missed dose means and which symptoms need urgent review. Read [Micronised Progesterone](/materials/micronised-progesterone/) and [Frozen Embryo Transfer](/treatments/fertility-and-assisted-reproduction/frozen-embryo-transfer/).