Frozen-warmed blastocyst transfer after 6 or 7 days of progesterone administration: impact on live birth rate in hormone replacement therapy cycles

Live birth rates are similar when frozen-thawed blastocysts are transferred on the 6th or 7th day of progesterone administration in artificially prepared cycles.

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Volume 114, Issue 1, Pages 125–132


Caroline Roelens, M.D., Samuel Santos-Ribeiro, M.D., Ph.D., Lauren Becu, M.D., Shari Mackens, M.D., Lisbet Van Landuyt, M.Sc., Ph.D., Annalisa Racca, M.D., Michel De Vos, M.D., Ph.D., Arne van de Vijver, M.D., Ph.D., Herman Tournaye, M.D., Ph.D., Christophe Blockeel, M.D., Ph.D.



To study the difference in live birth rate (LBR) between frozen-warmed blastocyst transfer (FET) on the 6th or the 7th day of progesterone administration in artificially prepared cycles.


Retrospective cohort study.


Tertiary university-based referral hospital.


Patients who underwent FET between December 2015 and December 2017 in a hormone replacement therapy cycle (HRT).


Group A included all eligible patients who underwent transfer of a vitrified-warmed blastocyst on the 6th day of progesterone administration; group B included patients who underwent blastocyst transfer on the 7th day of progesterone. The artificial HRT protocol in this study consisted of estrogen administration at a dose of 2 mg twice daily for 7 days followed by 2 mg three times daily for 6 days and micronized vaginal progesterone 200 mg three times daily from an adequately considered endometrial thickness onward.

Main Outcome Measure(s)

Live birth rate.


The study included 619 patients, 346 in group A and 273 in group B. The LBRs were comparable between both groups (36.6% for group A and group B), even after adjustment for confounding factors (adjusted odds ratio 1.073, 95% confidence interval 0.740–1.556). Subgroup analysis revealed significantly higher miscarriage rates for day 6 blastocysts transferred on the 6th day of progesterone supplementation compared with transfer on the 7th day of progesterone supplementation (50.0% versus 21.4%, respectively). Additionally, there was a tendency toward a higher LBR when the 7-day progesterone supplementation protocol was used for transfer of a day 6 blastocyst (21.5% and 35.5% for group A and group B, respectively).


Warmed blastocyst transfer on the 6th compared with the 7th day of progesterone administration in an HRT cycle results in similar LBR. Subgroup analysis of day 6 blastocysts showed significantly higher miscarriage rates when FET was performed on the 6th day of progesterone administration.

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Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders.