On Which Day of the Menstrual Cycle Does IVF Treatment Start?

On which day of the menstrual cycle does IVF treatment start?
IVF treatment typically begins on the second or third day of the menstrual cycle. This protocol is called the short protocol or antagonist protocol. At the start of menstruation, hormone levels in the blood drop to their baseline, and follicles are observed to be of equal and small size. This allows for maximum egg retrieval by stimulating all the follicles that are ready to grow with injections administered into the abdomen.
However, in patients over 40, due to elevated FSH hormone levels, there may be differences in follicle sizes, known as follicular asynchrony, at the start of menstruation. In such patients, it may be necessary to start the long protocol, also known as suppression therapy, on the 21st day of the cycle to synchronize the follicles. In cases of endometriosis, the long protocol may also be started on the 21st day to suppress cytokines released from endometriotic foci that can reduce the quality of eggs and embryos.
In patients at high risk of developing ovarian hyperstimulation syndrome (OHSS) from egg stimulation medication or in those where a total freeze of all embryos is planned after egg retrieval, progesterone suppression therapy can be initiated on the 2nd or 3rd day of the menstrual cycle, combining progesterone with injections.
On which day of the menstrual cycle is embryo transfer done?
In frozen embryo transfer, monitoring also begins on the 2nd or 3rd day of the menstrual cycle. In this treatment, the uterine lining is prepared either with estrogen and then a combination of estrogen and progesterone pills, or by tracking the natural growth of the egg to determine the day of embryo transfer.