In hormonally prepared frozen embryo transfer cycles, basal bilateral uterine artery Doppler velocimetry will be performed before treatment (pre-conceptional) in each patient. Only patients who have high-quality blastocyst stage embryos will be included in the study. Since the implantation potential of the specified embryos is high, possible embryo-induced implantation failure would be minimized.~Bilateral uterine artery Doppler velocimetry will be performed during the basal ultrasonography (on the 2-5th day of menstruation). Any uterine artery notch, absent diastolic or reverse flow also will be recorded. In addition, sub-endometrial (arcuate artery) blood flows will be evaluated by Doppler ultrasonography.~For endometrial preparation, estrogen replacement will be given for approximately 12-14 days as a routine In cases with endometrial thickness ≥7mm, progesterone treatment will be started and embryo transfer will be planned on the 6th day of the treatment.~A pregnancy test will be performed 9 days after embryo transfer. Pregnant patients will be called for ultrasonography control 3 weeks later to determine fetal heartbeat. Additionally, the patients will be followed till labor and any obstetric complications will be recorded.~Uterine artery Doppler ultrasonography findings in patients with and without pregnancy will be compared. Additionally, in the group in which pregnancy was achieved, obstetric results including birth weight, small-large for gestational age, presence of hypertension, and preterm labor will be correlated with baseline (pre-conceptional) uterine artery Doppler parameters.
Researchers aim to determine how baseline (pre-conceptional) uterine perfusion characteristics affect implantation rates and obstetric complications in women who underwent high-quality blastocyst transfer.