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.

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.

Inclusion Criteria:

• Exogenous hormone preparation of the endometrial lining
• High embryo quality ((≥2BB) according to Alpha criteria
• Embryo transfer at the blastocyst stage

Exclusion Criteria:

• Patients whose treatments were canceled for any reason before the embryo transfer procedure
• Patients who underwent embryo transfer in the cleavage stage
• Presence of low-quality (<2BB) blastocysts
• >15% loss of viability of the embryo during embryo thawing,
• Patients with congenital uterine malformations,
• Patients in whom Doppler velocimetry cannot be performed optimally

All patients who have artificial endometrial preparation with high-quality blastocysts between May 2022 and December 2022 will be included. All included patients will have bilateral uterine artery Doppler velocimetry on 2-5 days of their menstrual cycle by transvaginal ultrasonography.