Endometrial preparation and embryo transfer
Three main types of endometrial preparation protocols were applied: the
natural cycle (NC), hormone replacement treatment (HRT) cycle with or
without GnRH downregulation. In NC cycles, growth of follicles were
monitored under
transvaginal ultrasonography from cycle day 9 to 11. LH and estradiol
were measured every 3 days after the diameter of leading follicle ≥ 1.4
mm. Intramuscular progesterone injections (40 mg/day) were started at
the day of ovulation and FBT was scheduled on the 5th day after
ovulation. HRT was performed with 6-8 mg oral estradiol valerate daily
from cycle day 1 to day 14. Progesterone injection (60-100 mg) was
administrated as soon as the
endometrial thickness reached 7-8 mm
and then FBT was scheduled after 5 days of progesterone therapy. As for
HRT with GnRH- downregulation cycles, GnRH agonist was initiated on day
1 of the menstrual cycle. And on day 1 of subsequent menstruation,
estrogen stimulation was started as HRT cycles without GnRH agonist.
Embryo transfer was performed with a Guardia Access Embryo Transfer
catheter (K-JETS-7019-SIVF, Cook, IN, USA) under transabdominal
ultrasound guidance. Luteal support continued until 10 weeks of
pregnancy.