The Effectiveness of the Letrozole-induced Endometrial Preparation Protocol in Frozen-thawed Embryo Transfer (FET)

Experimental

No Intervention

Letrozole-induced endometrial preparation protocol

Hormone replacement cycles endometrial preparation protocol

Starting at D3 of the menstrual cycle, letrozole 2.5 mg po qd was administered for 5 days. After 1 week, ultrasound was performed to dynamically monitor follicular development, and 75-150 IU im qd of human menopausal gonadotrophin (hMG) given to continue ovulation stimulation as needed, and oestradiol valerate 2 mg po qd was given to regulate endometrial thickness until the follicle developed to 16 mm in diameter and 7 mm in endometrial thickness. The follicles developed to ≥16 mm in diameter and ≥7 mm in lining thickness and were dynamically monitored by ultrasound and serum sex hormone levels to determine the day of ovulation. From the day of ovulation, dexamethasone 10 mg po tid was administered, and cleavage-stage embryos were transferred 2 or 3 days later, or blastocysts were transferred 5 days later. Deferiprone 10 mg po tid was continued for 14 days after transfer.

Starting from D1-D5 of the menstrual cycle, estradiol valerate 2 mg po bid was administered for 7 days, followed by ultrasound for dynamic monitoring of endothelial and follicular development, and if the endothelial thickness was <7 mm, the dosage of estradiol valerate was increased to 3-4 mg po bid as appropriate. The number of days of hormone replacement ranged from 11-20 days, and when the endothelial thickness was 7 mm, luteinizing hormone vaginal slow-release gel 90 mg pv qd was added, as well as dexedrine and progesterone 10 mg po bid to transform the endothelium 2 or 3 days later or 5 days later. Progesterone 10 mg po bid was added to transform the endothelium, and cleavage stage embryos were transferred 2 or 3 days later, or blastocysts were transferred 5 days later. Luteal support as described above was continued for a total of 14 days after transfer.