Abstract:

Objective To investigate the influence of serum estradiol level on timing of embryo transfer and pregnancy outcome in hormone replacement-frozen embryo transfer cycles. Methods According to the oestradiol level on progesterone initiation day, 279 hormone replacement-frozen embryo transfer cycles were grouped into three groups (group 1, percentile 0-25th; group 2, percentile 26th-75th; group 3, percentile 76th-100th). The clinical characteristics and pregnancy outcomes in ovarian stimulation cycles and frozen embryo transfer cycles were compared among groups, and the serum estradiol and endometrium thickness on day 2 and day 12 of menstrual cycle and progesterone initiation day were compared among groups. Results There was no significant difference in clinical characteristics and pregnancy outcomes in ovarian stimulation cycles and frozen embryo transfer cycles among three groups (P>0.05). There was no significant difference in endometrium thickness on day 2 and day 12 of menstrual cycle and progesterone initiation day among three groups (P>0.05). Conclusion The serum estradiol level on progesterone initiation day may not influence endometrium thickness and pregnancy outcomes in hormone replacement-frozen embryo transfer cycles without pituitary downregulation.

Key words: oestradiol, frozen embryo transfer, pregnancy, endometrium