Prospective Randomized Control Study of Two Different Types of Luteal Phase Support in Natural Cycle Frozen Embryo Transfer and Its Effect on Pregnancy Rates

The rate of frozen embryos transfer (FET) has increased in recent years due to a higher tendency of single embryo transfer, use of preimplantation genetic testing, and prevention of ovarian hyperstimulation.

There are different methods to prepare the endometrium for FET:

1. Natural cycle (NC) - natural preparation of the body for implantation without the need for medicinal intervention.
2. Modified natural cycle (mNC) - Inducing ovulation by administration of Human Chorionic Gonadotropin (HCG) trigger.
3. Medical - preparation of endometrium with hormones (estrogen and progesterone).

Following embryo transfer, luteal phase support should be considered. Administration of treatment depends on the type of cycle chosen (either natural or medicated). Treatment options include progesterone, HCG and Gonadotropin Releasing Hormone (GnRH) analog - either one of them or combined. Different protocols (dosages and duration of use) with different pregnancy outcomes were explore before with inconclusive results. We wish to investigate administration of GnRH agonist+HCG vs. progesterone.

Patients included in the study will be women undergoing natural cycle FET at the IVF center in Shaare Zedek, Jerusalem, Israel. All patients will be randomly divided into two groups, each will receive a different luteal treatment support as will be detailed later. Patients demographic data and pregnancy outcomes will be collected.