Introduction
congenital malformations
With the success of improved cryopreservation techniques, pregnancy rates between fresh and frozen-thawed embryo transfer (FET) cycles are close to equal (Natural progesterone is a common therapeutic agent during LPS. It can be administered in different doses and ways, alone or in combination with estradiol, human chorionic gonadotropin (HCG), or gonadotropin-releasing hormone agonist (GnRH-a) (This study is a prospective randomized clinical pilot trial that evaluated the efficacy and safety of the additional single dose of GnRH-a at the time of implantation on the pregnancy outcome of patients undergoing hormonally substituted AC for FET. We also investigated the effect of GnRHa administration on the birth weights of the newborns and the rate of congenital malformations because GnRH-a is hypothesized that the hormone will alter the interaction of invading trophoblast and decidua, potentially affecting placentation.