Natural Versus Programmed Frozen Embryo Transfer (NatPro)

This treatment protocol is defined as a modified natural cycle as the participant will be instructed to (1) administer human chorionic gonadotropin (hCG) to assist with timing of the embryo transfer and (2) supplement the luteal phase with a low dose of progesterone.

This protocol is designated as programmed because the endometrial development occurs only in association with administration of estradiol and progesterone. No ovulation occurs due to suppression of follicle development by the estradiol and the timing of the transfer is based on the number of days elapsed following initiation of exogenous progesterone.