Impact of an estrogen replacement regimen on live birth rate in frozen-thawed good-quality embryo transfer.

OBJECTIVE

To assess the impact of an estrogen replacement regimen on frozen embryo transfer (FET) cycle outcome.

METHODS

In the present retrospective cohort study, data of infertile women undergoing FET with good-quality embryos were reviewed. The first group received 2 mg of estradiol hemihydrate (EH) once daily for 6 to 7 days, then twice daily for 4 to 5 days, and then three times a day until embryo transfer. The second group received EH twice daily for 7 to 8 days, then three times a day. The third group received EH three times a day constantly. The main outcome measure was live birth rate.

RESULTS

In total, 394 FET cycles were included. The fixed 6-mg group required the highest estradiol hemihydrate dose. The duration of estrogen treatment was significantly longer in the first group. Maximal endometrial thickness was highest in the second group (10.2 ± 1.3 mm vs. 9.6 ± 1.4 mm vs. 8.6 ± 0.9 mm, respectively; P < 0.001). The clinical pregnancy rates in the groups were 41.1%, 55.2%, and 42.2%, respectively (P = 0.035). Live birth rates were 40.8%, 50.9%, and 48.1%, respectively (P = 0.320).

CONCLUSION

In FET cycles with hormone replacement therapy, a step-up 4-mg regimen provides thicker endometrium with optimal-dose estrogen in an adequate time frame. The tendency for increased clinical pregnancy and live birth rates is remarkable.