Serum luteal phase progesterone in women undergoing frozen embryo transfer in assisted conception: a systematic review and meta-analysis

For thresholds <10 ng/mL, women with lower serum progesterone levels experience fewer live births and increased risk of miscarriage compared with those of women with higher serum progesterone levels.

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VOLUME 116, ISSUE 6, P1534-1556


Pedro Melo, M.D., Yealin Chung, M.B.B.S., Oonagh Pickering, B.Sc., Malcolm J. Price, Ph.D., Simon Fishel, Ph.D., Mohammed Khairy, M.D., Charles Kingsland, M.D., Philip Lowe, M.B.Ch.B., Georgios Petsas, M.D., Ph.D., Madhurima Rajkhowa, M.D., Victoria Sephton, M.B.Ch.B., Amanda Tozer, M.B.Ch.B., Simon Wood, M.D., Elena Labarta, M.D., Ph.D., Mark Wilcox, D.M., Adam Devall, Ph.D., Ioannis Gallos, M.D., Arri Coomarasamy, M.D.



To investigate the association between luteal serum progesterone levels and frozen embryo transfer (FET) outcomes.


Systematic review and meta-analysis.


Not applicable.


Women undergoing FET.


We conducted electronic searches of MEDLINE, PubMed, CINAHL, EMBASE, the Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Web of Science,, and grey literature (not widely available) from inception to March 2021 to identify cohort studies in which the serum luteal progesterone level was measured around the time of FET.

Main Outcome Measure(s)

Ongoing pregnancy or live birth rate, clinical pregnancy rate, and miscarriage rate.


Among the studies analyzing serum progesterone level thresholds <10 ng/mL, a higher serum progesterone level was associated with increased rates of ongoing pregnancy or live birth (relative risk [RR] 1.47, 95% confidence interval [CI] 1.28 to 1.70), higher chance of clinical pregnancy (RR 1.31, 95% CI 1.16 to 1.49), and lower risk of miscarriage (RR 0.62, 95% CI 0.50 to 0.77) in cycles using exclusively vaginal progesterone and blastocyst embryos. There was uncertainty about whether progesterone thresholds ≥10 ng/mL were associated with FET outcomes in sensitivity analyses including all studies, owing to high interstudy heterogeneity and wide CIs.


Our findings indicate that there may be a minimum clinically important luteal serum concentration of progesterone required to ensure an optimal endocrine milieu during embryo implantation and early pregnancy after FET treatment. Future clinical trials are required to assess whether administering higher-dose luteal phase support improves outcomes in women with a low serum progesterone level at the time of FET.



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.