SHorter Treatment of Replacement Therapy for Frozen Embryo Transfer (FET)

All women included will take exogenous hormone with daily administration of Estradiol Valerate (Progynova®), the standard dose used will be 6 mg/day (Cobo et al., n.d.). On day 7 of endometrial preparation patients will be examined with vaginal ultrasound and blood test, to evaluate the endometrial thickness and the hormones levels. In both arms the FET will take place after 6 days of Progesterone supplementation (600 mg per day, vaginal administration of Utrogestan®) According to embryo quality after warming, embryo transfer to the uterine cavity will be performed on day 5 of development under ultrasound guidance whenever possible. Following embryo transfer, luteal support will be continued with vaginally administered P (Utrogestan®). All patients 12 days after the FET will undergo the pregnancy test (blood test to evaluate hCG).