In IVF, what is the purpose of luteal-phase progesterone supplementation after embryo transfer?

• A. It is not used in IVF and has no role.
• B. It is only used in ovulation induction cycles.
• C. It is routinely used after embryo transfer to support endometrial receptivity.
• D. It replaces the need for ovarian stimulation.

Answer: (C)

The main idea is that progesterone during the luteal phase is essential to make the lining of the uterus receptive to an embryo and to support early pregnancy. In typical IVF cycles, the hormonal setup from stimulation and suppression of natural luteal function can leave the endometrium under-protected and not properly secretory. Providing progesterone after embryo transfer maintains a secretory endometrium and supports implantation and early pregnancy until the placenta takes over progesterone production, usually in the first trimester. This is why luteal-phase progesterone is routinely used after embryo transfer. It works alongside the IVF protocol and does not replace ovarian stimulation. Progesterone can be delivered vaginally, intramuscularly, or as a pessary, and is continued until the placenta can sustain progesterone levels.