Ovarian stimulation protocol, endometrial preparation protocol,
ET process, and luteal support
A personalized controlled ovarian hyperstimulation (COH) protocol was
chosen for each patient according to her age, anti-Müllerian hormone
level, body mass index (BMI), number of antral follicles in the
bilateral ovaries, and prior response to stimulation13-15. Follicular development was determined by
transvaginal ultrasonography, and the dosages of gonadotropin were
adjusted according to different ovarian responses.
When the follicles reached a diameter
of more than 17 mm, the trigger was performed for final oocyte
maturation. Oocyte retrieval was performed 36 hours after triggering
with transvaginal ultrasound-guided aspiration.
Endometrial preparation for FET used the HRT cycle, wherein 4-8 mg of
estradiol valerate (Progynova, Bayer, Germany) was administered orally
for at least 10 days from the 3rd to 5th days of menstruation to promote
endometrial growth. The cut-off value for endometrial transformation was
more than 8 mm. The embryos were slowly injected 10 mm from the uterine
fundus under ultrasound guidance, and the catheter remained in situ for
3-5 seconds. The patients subsequently stood upright and walked to the
rest area, where they lay in bed for 20-30 min before leaving.
The luteal phase was supported by vaginal administration of progesterone
gel (Crinone, Fleet Laboratories Ltd., UK) at 90 mg/day, while estradiol
was maintained at the original dose. Luteal support was continued until
11 weeks of gestational age.