{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,10]],"date-time":"2025-12-10T12:05:18Z","timestamp":1765368318186,"version":"build-2065373602"},"reference-count":36,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,10,1]],"date-time":"2025-10-01T00:00:00Z","timestamp":1759276800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Med."],"abstract":"<jats:sec><jats:title>Objective<\/jats:title><jats:p>The aim of this study was to compare the effects of different endometrial treatment regimens on the outcome of frozen embryo transfer (FET).<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>A retrospective analysis of 1,454 FET cycles was conducted. Subgroups were stratified by primary infertility diagnosis (tubal factor, polycystic ovary syndrome (PCOS), and endometriosis) and by the number of embryos transferred. Multivariable logistic regression was employed to identify factors influencing live birth.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Our study found that endometrial thickness on the day of embryo transfer was thicker in the gonadotropin-releasing hormone agonist (GnRHa)\u2013hormone replacement therapy (HRT) group compared to the HRT group (<jats:italic>p<\/jats:italic>\u202f=\u202f0.000), the levels of estrogen and progesterone in GnRHa\u2013HRT group were lower than HRT group, and there were no statistically significant differences in other baseline characteristics between the two groups. The live birth rate in the single embryo transfer GnRHa\u2013HRT group was higher than that of HRT(OR\u202f=\u202f1.489, 95%CI:1.070\u20132.073). Within the tubal\/male factor cohort, spontaneous abortion rate was slightly more frequent in the GnRHa\u2013HRT group (<jats:italic>p<\/jats:italic>\u202f=\u202f0.899). In the PCOS\u2013endometriosis (EMs) subgroup, the spontaneous abortion rate had a decreasing trend, but the difference was not statistically significant (<jats:italic>p<\/jats:italic>\u202f&amp;gt;\u202f0.05). Binary logistic regression analysis further confirmed the negative influence of age on live birth.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>The GnRHa\u2013HRT significantly improves live birth rates compared to the conventional HRT in single-embryo transfer cycles. Downregulation protocols may be a priority for patients with endometriosis and single embryo transfer. For patients with PCOS and tubal factors, the HRT program is more cost-effective and takes less time to achieve pregnancy. These findings provide evidence-based guidance for individualized endometrial preparation regimen selection in FET cycles, though the retrospective design and lack of long-term follow-up limit the generalizability. Future prospective randomized controlled trials with larger sample sizes are warranted to validate these conclusions.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fmed.2025.1649012","type":"journal-article","created":{"date-parts":[[2025,10,1]],"date-time":"2025-10-01T05:52:24Z","timestamp":1759297944000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["GnRH agonist pretreatment in hormonal endometrial preparation: a comparison of two protocols for frozen embryo transfer outcomes"],"prefix":"10.3389","volume":"12","author":[{"given":"Xi","family":"Yi","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dongmei","family":"Tian","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hengli","family":"Li","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guanhua","family":"Zhou","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2025,10,1]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"19","DOI":"10.1016\/j.fertnstert.2014.05.027","article-title":"Cryopreservation of human embryos and its contribution to in vitro fertilization success rates","volume":"102","author":"Wong","year":"2014","journal-title":"Fertil Steril"},{"key":"ref2","doi-asserted-by":"publisher","first-page":"1193826","DOI":"10.3389\/fendo.2023.1193826","article-title":"Association between duration of progesterone supplementation and clinical outcomes in artificial frozen-thawed embryo transfer cycles","volume":"14","author":"Liu","year":"2023","journal-title":"Front Endocrinol"},{"key":"ref3","doi-asserted-by":"publisher","first-page":"164","DOI":"10.31083\/j.ceog5107164","article-title":"Effect of high serum Estradiol levels and duration of vaginal Estradiol administration on reproductive outcomes in frozen-thawed embryo transfer cycles","volume":"51","author":"Zhang","year":"2024","journal-title":"CEOG"},{"key":"ref4","doi-asserted-by":"publisher","first-page":"2234","DOI":"10.1093\/humrep\/dex285","article-title":"Frozen embryo transfer: a review on the optimal endometrial preparation and timing","volume":"32","author":"Mackens","year":"","journal-title":"Hum Reprod"},{"key":"ref5","doi-asserted-by":"publisher","first-page":"12","DOI":"10.3389\/fendo.2021.722253","article-title":"Endometrial preparation for frozen\u2013thawed embryo transfer with or without Pretreatment with GnRH agonist: a randomized controlled trial at two Centers","author":"Xu","year":"2021","journal-title":"Front Endocrinol"},{"key":"ref6","doi-asserted-by":"publisher","first-page":"1014558","DOI":"10.3389\/fendo.2022.1014558","article-title":"GnRH-agonist pretreatment in hormone replacement therapy improves pregnancy outcomes in women with male-factor infertility","volume":"13","author":"Yu","year":"2022","journal-title":"Front Endocrinol"},{"key":"ref7","doi-asserted-by":"publisher","first-page":"847","DOI":"10.1093\/humrep\/deh183","article-title":"Pituitary suppression in ultrasound-monitored frozen embryo replacement cycles. A randomised study","volume":"19","author":"El-Toukhy","year":"","journal-title":"Hum Reprod."},{"key":"ref8","doi-asserted-by":"publisher","first-page":"11","DOI":"10.3389\/fmed.2024.1412126","article-title":"The effect of gonadotropin-releasing hormone agonist downregulation in conjunction with hormone replacement therapy on endometrial preparation in patients for frozen\u2013thawed embryo transfer","author":"Hao","year":"2024","journal-title":"Front Med"},{"key":"ref9","doi-asserted-by":"publisher","first-page":"171","DOI":"10.31083\/j.ceog5008171","article-title":"Gonadotropin-releasing hormone agonist combined with hormone replacement therapy protocol improves the live birth rate in frozen-thawed embryo transfer cycles for patients without endometriosis","volume":"50","author":"Wang","year":"2023","journal-title":"CEOG"},{"key":"ref10","doi-asserted-by":"publisher","first-page":"405","DOI":"10.1093\/molehr\/2.6.405","article-title":"Cytokines-adhesion molecules-invasive proteinases. 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