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Endocrinol."],"abstract":"<jats:sec><jats:title>Research question<\/jats:title><jats:p>The main objective of the study is to define the optimal trade-off progesterone (P4) values on the day of embryo transfer (ET), to identify low P4-human chorionic gonadotropin (hCG), and to establish whether P4 supplementation started on the hCG day can increase the success rate of the frozen embryo transfer (FET) cycle.<\/jats:p><\/jats:sec><jats:sec><jats:title>Design<\/jats:title><jats:p>A single-center, cohort, retrospective study with 664 hormone replacement therapy (HRT)-FET cycles analyzed female patients who received vaginal 600 mg\/day of P4 starting from 6 days before the FET, had normal P4 values on the day before ET, and whose P4 on the day of the pregnancy test was assessed.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Of the 664 cycles, 69.6% of cycles showed P4 <jats:bold>\u2265<\/jats:bold> 10.6 ng\/ml, while 30.4% showed P4 &amp;lt; 10.6 ng\/ml on the day of the hCG. Of the 411 chemical pregnancies detected, 71.8% had P4-hCG <jats:bold>\u2265<\/jats:bold> 10.6 ng\/ml (group A), while 28.2% had P4-hCG &amp;lt; 10.6 ng\/ml. Of the cycles with P4-hCG &amp;lt; 10.6 ng\/ml, 64.7% (group B) were supplemented with a higher dose of vaginal P4 (1,000 mg\/day), while 35.3% (group C) were maintained on the same dose of vaginal micronized P4. The live birth rate was 71.9%, 96%, and 7.3% for groups A, B, and C, respectively.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>The likelihood to detect P4-hCG &amp;lt; 10.6 ng\/ml decreased as the level of serum P4 the day before ET increased. The live birth rate (LBR) was shown to be significantly lower when P4 was low and not supplemented.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fendo.2023.1090105","type":"journal-article","created":{"date-parts":[[2023,2,1]],"date-time":"2023-02-01T06:57:17Z","timestamp":1675234637000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":13,"title":["Assessment of progesterone levels on the day of pregnancy test determination: A novel concept toward individualized luteal phase support"],"prefix":"10.3389","volume":"14","author":[{"given":"A.","family":"Racca","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M.","family":"Alvarez","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"S.","family":"Garcia Martinez","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"I.","family":"Rodriguez","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"I.","family":"Gonzalez-Foruria","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"NP.","family":"Polyzos","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"B.","family":"Coroleu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2023,2,1]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"2","DOI":"10.1016\/j.clinbiochem.2018.03.012","article-title":"Fertility and infertility: Definition and epidemiology","volume":"62","author":"Vander Borght","year":"2018","journal-title":"Clin Biochem"},{"key":"B2","doi-asserted-by":"publisher","DOI":"10.1093\/humrep\/dez233","article-title":"Should we still perform fresh embryo transfers in ART","volume":"34","author":"Blockeel","year":"2019","journal-title":"Hum Reprod"},{"key":"B3","doi-asserted-by":"publisher","DOI":"10.1093\/humrep\/deaa250","article-title":"20 years of the european IVF-monitoring consortium registry: What have we learned? a comparison with registries from two other regions","volume":"35","author":"De Geyter","year":"2020","journal-title":"Hum Reprod"},{"key":"B4","doi-asserted-by":"publisher","DOI":"10.1093\/humrep\/dex285","article-title":"Frozen embryo transfer: A review on the optimal endometrial preparation and timing","volume":"32","author":"Mackens","year":"2017","journal-title":"Hum Reprod Oxf Engl"},{"key":"B5","doi-asserted-by":"publisher","first-page":"27","DOI":"10.1186\/1472-6874-12-27","article-title":"ANTARCTICA trial study group. cryo-thawed embryo transfer: natural versus artificial cycle. a non-inferiority trial. 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