{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,5]],"date-time":"2026-09-05T00:12:57Z","timestamp":1788567177083,"version":"build-2803163510"},"reference-count":35,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2024,6,12]],"date-time":"2024-06-12T00:00:00Z","timestamp":1718150400000},"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. Endocrinol."],"abstract":"<jats:sec><jats:title>Introduction<\/jats:title><jats:p>The utilization of frozen embryo transfer not only enhances reproductive outcomes by elevating the likelihood of live birth and clinical pregnancy but also improves safety by mitigating the risks associated with ovarian hyperstimulation syndrome (OHSS) and multiple pregnancies. There has been an increasing debate in recent years regarding the advisability of making elective frozen embryo transfer the standard practice. Our study aims to determine the optimal choice between fresh and frozen embryo transfer, as well as whether the transfer should occur at the cleavage or blastocyst stage.<\/jats:p><\/jats:sec><jats:sec><jats:title>Method<\/jats:title><jats:p>In this retrospective cohort study conducted in Taiwan, data from the national assisted reproductive technology (ART) database spanning from January 1st, 2013, to December 31st, 2017, were analyzed. The study included 51,762 eligible female participants who underwent ART and embryo transfer. Pregnancy outcomes, maternal complications, and singleton neonatal outcomes were evaluated using the National Health Insurance Database from January 1st, 2013, to December 31st, 2018. Cases were categorized into groups based on whether they underwent fresh or frozen embryo transfers, with further subdivision into cleavage stage and blastocyst stage transfers. Exposure variables encompassed clinical pregnancy rate, live birth rate, OHSS, pregnancy-induced hypertension, gestational diabetes mellitus (DM), placenta previa, placental abruption, preterm premature rupture of membranes (PPROM), gestational age, newborn body weight, and route of delivery.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Frozen blastocyst transfers showed higher rates of clinical pregnancy (CPR) and live births (LBR) compared to fresh blastocyst transfers. Conversely, frozen cleavage stage transfers demonstrated lower rates of clinical pregnancy and live birth compared to fresh cleavage stage transfers. Frozen embryo transfers were associated with reduced risks of OHSS but were linked to a higher risk of pregnancy-induced hypertension compared to fresh embryo transfers. Additionally, frozen embryo transfers were associated with a higher incidence of large for gestational age infants and a lower incidence of small for gestational age infants.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>The freeze-all strategy may not be suitable for universal application. When embryos can develop to the blastocyst stage, FET is a favorable choice, but embryos can only develop to the cleavage stage, fresh embryo transfer becomes a more reasonable option.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fendo.2024.1400255","type":"journal-article","created":{"date-parts":[[2024,6,12]],"date-time":"2024-06-12T04:32:41Z","timestamp":1718166761000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":7,"title":["Embryo transfer impact: a comprehensive national cohort analysis comparing maternal and neonatal outcomes across varied embryo stages in fresh and frozen transfers"],"prefix":"10.3389","volume":"15","author":[{"given":"Chih-Ting","family":"Chang","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shih-Feng","family":"Weng","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hui-Yu","family":"Chuang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"I-Le","family":"Hsu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chia-Yi","family":"Hsu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eing-Mei","family":"Tsai","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2024,6,12]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1093\/humrep\/14.6.1457","article-title":"Elective cryopreservation of all pronucleate embryos in women at risk of ovarian hyperstimulation syndrome: efficiency and safety","volume":"14","author":"Ferraretti","year":"1999","journal-title":"Hum Reprod"},{"key":"B2","doi-asserted-by":"publisher","DOI":"10.1016\/j.fertnstert.2012.09.003","article-title":"Fresh embryo transfer versus frozen embryo transfer in in vitro fertilization cycles: a systematic review and meta-analysis","volume":"99","author":"Roque","year":"2013","journal-title":"Fertil Steril"},{"key":"B3","doi-asserted-by":"publisher","first-page":"2","DOI":"10.1093\/humupd\/dmy033","article-title":"Fresh versus elective frozen embryo transfer in IVF\/ICSI cycles: a systematic review and meta-analysis of reproductive outcomes","volume":"25","author":"Roque","year":"2019","journal-title":"Hum Reprod Update"},{"key":"B4","doi-asserted-by":"publisher","DOI":"10.1016\/j.fertnstert.2022.10.021","article-title":"Fresh vs. frozen embryo transfer: new approach to minimize the limitations of using national surveillance data for clinical research","volume":"119","author":"Weiss","year":"2023","journal-title":"Fertil Steril"},{"key":"B5","doi-asserted-by":"publisher","DOI":"10.1007\/s10815-020-01934-z","article-title":"A freeze-all strategy does not increase live birth rates in women of advanced reproductive age","volume":"37","author":"Lattes","year":"2020","journal-title":"J Assist Reprod Genet"},{"key":"B6","doi-asserted-by":"publisher","DOI":"10.26355\/eurrev_202307_33152","article-title":"Fresh vs. frozen embryo transfer in assisted reproductive techniques: a single center retrospective cohort study and ethical-legal implications","volume":"27","author":"Gullo","year":"2023","journal-title":"Eur Rev Med Pharmacol Sci"},{"key":"B7","doi-asserted-by":"publisher","DOI":"10.1093\/humrep\/deac126","article-title":"Pro: Fresh versus frozen embryo transfer. 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