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Live birth rates with a freeze-only strategy versus fresh embryo transfer: secondary analysis of a randomized clinical trial

DOI: 10.1016/j.rbmo.2018.12.012

Reproductive Biomedicine Online, Volume 38, Issue 3, pp. 387–396 – 2019-03-01

Lan N. Vuong1,2,*, Toan D. Pham2, Vinh Q. Dang2, Tuong M. Ho2, Vu N. A. Ho2, Robert J. Norman3,4, Ben W. Mol5

Published: December 20, 2018

Author information


Research question: What are the roles of serum progesterone and endometrial thickness as biomarkers in the decision between a freeze-only and fresh embryo transfer in IVF for women without polycystic ovary syndrome (PCOS)?
Design: This was a secondary analysis of a randomized controlled trial including 782 couples who were followed up until the end of the frst completed cycle. Couples scheduled for their first or second IVF cycle with a FSH/gonadotrophin-releasing hormone antagonist protocol were randomized to a freeze-only (n = 391) or fresh embryo transfer (n = 391) strategy. The endpoint for this analysis was live birth rate (LBR) after the first embryo transfer.
Results: There was no signifcant difference in LBR after the frst cycle between a freeze-only and fresh transfer strategy. When serum progesterone levels at trigger were in the third quartile (Q3, 1.14–1.53 ng/ml), LBR was signifcantly higher in the freeze-only versus fresh transfer group (P = 0.01); when serum progesterone was ≥1.14 ng/ml, LBR was signifcantly better in the freeze-only group (37.4% versus 23.8% in the fresh transfer group; P = 0.004). LBRs in the freeze-only and fresh embryo transfer groups were similar across all quartiles of endometrial thickness, although a small advantage for freeze-only in women with a very thin endometrium could not be excluded.
Conclusions: Serum progesterone level on the day of trigger may have potential as a biomarker on which to base a prospective decision about whether to use a freeze-only or fresh embryo transfer strategy in women undergoing IVF


IVF Biomarkers, Endometrial thickness, Freeze-only protocol, Progesterone, Randomized clinical trial