{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T07:38:41Z","timestamp":1787729921396,"version":"build-2784847793"},"reference-count":47,"publisher":"Georg Thieme Verlag KG","issue":"08","license":[{"start":{"date-parts":[[2020,8,14]],"date-time":"2020-08-14T00:00:00Z","timestamp":1597363200000},"content-version":"vor","delay-in-days":13,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Geburtshilfe Frauenheilkd"],"published-print":{"date-parts":[[2020,8]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>While widely used for ovulation induction in assisted reproductive technology, the clinical efficacy of letrozole for endometrial preparation prior to frozen-thawed embryo transfer (FET) cycles remains yet to be elucidated. We performed a meta-analysis to compare pregnancy outcomes after letrozole use with those of other endometrial preparation protocols in patients undergoing FET. PubMed, Scopus, Embase and the Cochrane Library were searched for eligible studies. Clinical pregnancy rate (CPR), live birth rate (LBR) and birth defect rate (BDR) were analysed using odds ratio (OR) and 95% confidence interval (CI). A total of 10 studies representing 75\u200a968 FET cycles were included. Comparable CPR and LBR were observed when comparing letrozole administration with natural cycle (OR 1.24, 95% CI: 0.69\u200a\u2013\u200a2.24; OR 1.18, 95% CI: 0.60\u200a\u2013\u200a2.32), artificial cycle (OR 1.46, 95% CI: 0.87\u200a\u2013\u200a2.44; OR 1.39, 95% CI: 0.77\u200a\u2013\u200a2.52), and artificial cycle with gonadotropin-releasing hormone agonist suppression (OR 1.11, 95% CI: 0.78\u200a\u2013\u200a1.59; OR 1.18, 95% CI: 0.82\u200a\u2013\u200a1.68). Pooled results of the limited studies comparing letrozole with human menopausal gonadotropin demonstrated a similar CPR between groups (OR 1.46, 95% CI: 0.29\u200a\u2013\u200a7.21, two studies), but the letrozole group had a statistically lower LBR (OR 0.67, 95% CI: 0.52\u200a\u2013\u200a0.86, one study). No increased BDR was observed in the letrozole group compared to natural cycles or artificial cycles (OR 0.98, 95% CI: 0.60\u200a\u2013\u200a1.61; OR 1.39, 95% CI; 0.84\u200a\u2013\u200a2.28). This pooled analysis supports the use of letrozole as an efficacious and safe alternative to mainstream regimens for endometrial preparation in FET cycles.<\/jats:p>","DOI":"10.1055\/a-1202-2059","type":"journal-article","created":{"date-parts":[[2020,8,14]],"date-time":"2020-08-14T23:06:49Z","timestamp":1597446409000},"page":"820-833","source":"Crossref","is-referenced-by-count":17,"title":["Pregnancy Outcomes Following Letrozole Use in Frozen-thawed Embryo Transfer Cycles: A Systematic Review and Meta-analysis"],"prefix":"10.1055","volume":"80","author":[{"given":"Dongjia","family":"Chen","sequence":"additional","affiliation":[{"name":"Reproductive Medicine Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China"},{"name":"Guangdong Provincial Key Laboratory of Reproductive Medicine, Guangzhou, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoting","family":"Shen","sequence":"additional","affiliation":[{"name":"Reproductive Medicine Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China"},{"name":"Guangdong Provincial Key Laboratory of Reproductive Medicine, Guangzhou, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yu","family":"Fu","sequence":"additional","affiliation":[{"name":"Reproductive Medicine Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China"},{"name":"Guangdong Provincial Key Laboratory of Reproductive Medicine, Guangzhou, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chenhui","family":"Ding","sequence":"additional","affiliation":[{"name":"Reproductive Medicine Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China"},{"name":"Guangdong Provincial Key Laboratory of Reproductive Medicine, Guangzhou, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yiping","family":"Zhong","sequence":"additional","affiliation":[{"name":"Reproductive Medicine Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China"},{"name":"Guangdong Provincial Key Laboratory of Reproductive Medicine, Guangzhou, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Canquan","family":"Zhou","sequence":"additional","affiliation":[{"name":"Reproductive Medicine Center, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China"},{"name":"Guangdong Provincial Key Laboratory of Reproductive Medicine, Guangzhou, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"194","published-online":{"date-parts":[[2020,8,14]]},"reference":[{"key":"ref1","doi-asserted-by":"crossref","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":"M Roque","year":"2019","journal-title":"Hum Reprod Update"},{"key":"ref2","doi-asserted-by":"crossref","first-page":"523","DOI":"10.1056\/NEJMoa1513873","article-title":"Fresh versus Frozen Embryos for Infertility in the Polycystic Ovary Syndrome","volume":"375","author":"Z J Chen","year":"2016","journal-title":"N Engl J Med"},{"key":"ref3","doi-asserted-by":"crossref","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":"S Mackens","year":"2017","journal-title":"Hum Reprod"},{"issue":"07","key":"ref4","doi-asserted-by":"publisher","DOI":"10.1002\/14651858.CD003414.pub3","article-title":"Cycle regimens for frozen-thawed embryo transfer","author":"T Ghobara","year":"2017","journal-title":"Cochrane Database Syst Rev"},{"key":"ref5","first-page":"138","article-title":"Comparison of Letrozole and Clomiphene Citrate Efficacy along with Gonadotrophins in Controlled Ovarian Hyperstimulation for Intrauterine Insemination Cycles","volume":"14","author":"F Haqnawaz","year":"2013","journal-title":"J Reprod Infertil"},{"key":"ref6","doi-asserted-by":"crossref","first-page":"571","DOI":"10.1093\/humupd\/dmn033","article-title":"Use of letrozole in assisted reproduction: a systematic review and meta-analysis","volume":"14","author":"A Requena","year":"2008","journal-title":"Hum Reprod Update"},{"key":"ref7","doi-asserted-by":"crossref","first-page":"170","DOI":"10.4103\/0974-1208.101014","article-title":"Letrozole in a low-cost in vitro fertilization protocol in intracytoplasmic sperm injection cycles for male factor infertility: A randomized controlled trial","volume":"5","author":"S Mukherjee","year":"2012","journal-title":"J Hum Reprod Sci"},{"key":"ref8","doi-asserted-by":"crossref","first-page":"872","DOI":"10.1016\/j.fertnstert.2018.01.008","article-title":"Ovarian stimulation in infertile women treated with the use of intrauterine insemination: a cohort study from China","volume":"109","author":"S Huang","year":"2018","journal-title":"Fertil Steril"},{"key":"ref9","doi-asserted-by":"crossref","first-page":"305","DOI":"10.1016\/S0015-0282(00)01705-2","article-title":"Use of an aromatase inhibitor for induction of ovulation in patients with an inadequate response to clomiphene citrate","volume":"75","author":"M F Mitwally","year":"2001","journal-title":"Fertil Steril"},{"issue":"05","key":"ref10","doi-asserted-by":"publisher","DOI":"10.1002\/14651858.CD010287.pub3","article-title":"Aromatase inhibitors (letrozole) for subfertile women with polycystic ovary syndrome","author":"S Franik","year":"2018","journal-title":"Cochrane Database Syst Rev"},{"key":"ref11","doi-asserted-by":"crossref","first-page":"364","DOI":"10.1016\/j.fertnstert.2018.05.004","article-title":"Recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome","volume":"110","author":"H J Teede","year":"2018","journal-title":"Fertil Steril"},{"key":"ref12","doi-asserted-by":"crossref","first-page":"1631","DOI":"10.1093\/humrep\/dex227","article-title":"Double-blind randomized controlled trial of letrozole versus clomiphene citrate in subfertile women with polycystic ovarian syndrome","volume":"32","author":"S A Amer","year":"2017","journal-title":"Hum Reprod"},{"key":"ref13","doi-asserted-by":"crossref","first-page":"110","DOI":"10.1016\/j.fertnstert.2004.05.099","article-title":"Hormonal profile and endometrial morphology in letrozole-controlled ovarian hyperstimulation in ovulatory infertile patients","volume":"83","author":"A Cortinez","year":"2005","journal-title":"Fertil Steril"},{"key":"ref14","doi-asserted-by":"crossref","first-page":"105","DOI":"10.3109\/19396368.2013.862316","article-title":"Endometrial receptivity markers in infertile women stimulated with letrozole compared with clomiphene citrate and natural cycles","volume":"60","author":"A Ganesh","year":"2014","journal-title":"Syst Biol Reprod Med"},{"key":"ref15","doi-asserted-by":"crossref","first-page":"64","DOI":"10.1002\/uog.18933","article-title":"Effect of clomiphene citrate on endometrial thickness, ovulation, pregnancy and live birth in anovulatory women: systematic review and meta-analysis","volume":"51","author":"M A Gadalla","year":"2018","journal-title":"Ultrasound Obstet Gynecol"},{"key":"ref16","doi-asserted-by":"crossref","first-page":"b2700","DOI":"10.1136\/bmj.b2700","article-title":"The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate healthcare interventions: explanation and elaboration","volume":"339","author":"A Liberati","year":"2009","journal-title":"BMJ"},{"key":"ref20","doi-asserted-by":"crossref","first-page":"83","DOI":"10.29252\/ijrm.15.2.83","article-title":"Can letrozole plus HMG protocol improve pregnancy outcomes in frozen-thawed embryo transfer? An RCT","volume":"15","author":"A Aleyasin","year":"2017","journal-title":"Int J Reprod Biomed (Yazd)"},{"key":"ref21","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1515\/jbcpp-2012-0052","article-title":"Frozen embryo transfer: the present practice and beyond","volume":"24","author":"A R Chaudhuri","year":"2013","journal-title":"J Basic Clin Physiol Pharmacol"},{"key":"ref22","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1080\/19396368.2016.1199064","article-title":"A modified natural cycle results in higher live birth rate in vitrified-thawed embryo transfer for women with regular menstruation","volume":"62","author":"Y Guan","year":"2016","journal-title":"Syst Biol Reprod Med"},{"key":"ref23","first-page":"1","article-title":"Different endometrial preparation protocols yield similar pregnancy outcomes for frozen-thawed embryo transfer in patients with advanced endometriosis","volume":"27","author":"H Y Guo","year":"2016","journal-title":"Reprod Contracept"},{"key":"ref24","doi-asserted-by":"crossref","first-page":"283","DOI":"10.1111\/cen.12280","article-title":"Letrozole stimulation in endometrial preparation for cryopreserved-thawed embryo transfer in women with polycystic ovarian syndrome: a pilot study","volume":"80","author":"Y J Hu","year":"2014","journal-title":"Clin Endocrinol (Oxf)"},{"key":"ref25","doi-asserted-by":"crossref","first-page":"772","DOI":"10.1080\/09513590.2018.1460342","article-title":"Modified hMG stimulated: an effective option in endometrial preparation for frozen-thawed embryo transfer in patients with normal menstrual cycles","volume":"34","author":"P Huang","year":"2018","journal-title":"Gynecol Endocrinol"},{"key":"ref26","doi-asserted-by":"crossref","first-page":"96","DOI":"10.1016\/j.mefs.2015.09.002","article-title":"Letrozole versus artificial hormonal endometrial preparation for vitrified-warmed embryos transfer cycles","volume":"21","author":"H Sibai","year":"2016","journal-title":"Middle East Fertil Soc J"},{"key":"ref27","doi-asserted-by":"crossref","first-page":"1244","DOI":"10.1093\/humrep\/dex066","article-title":"Pregnancy and neonatal outcomes following letrozole use in frozen-thawed single embryo transfer cycles","volume":"32","author":"T Tatsumi","year":"2017","journal-title":"Hum Reprod"},{"key":"ref28","doi-asserted-by":"crossref","first-page":"371","DOI":"10.1016\/j.fertnstert.2019.04.014","article-title":"Letrozole use during frozen embryo transfer cycles in women with polycystic ovary syndrome","volume":"112","author":"J Zhang","year":"2019","journal-title":"Fertil Steril"},{"key":"ref29","doi-asserted-by":"crossref","first-page":"687","DOI":"10.1007\/s00404-013-3044-0","article-title":"Letrozole ovulation induction: an effective option in endometrial preparation for frozen-thawed embryo transfer","volume":"289","author":"S J Li","year":"2014","journal-title":"Arch Gynecol Obstet"},{"key":"ref30","doi-asserted-by":"crossref","first-page":"915","DOI":"10.1016\/j.fertnstert.2015.07.1131","article-title":"Randomized, controlled pilot trial of natural versus hormone replacement therapy cycles in frozen embryo replacement in vitro fertilization","volume":"104","author":"G Mounce","year":"2015","journal-title":"Fertil Steril"},{"key":"ref31","doi-asserted-by":"crossref","first-page":"626","DOI":"10.1007\/s11596-018-1923-0","article-title":"Artificial Cycle with or without a Depot Gonadotropin-releasing Hormone Agonist for Frozen-thawed Embryo Transfer: An Assessment of Infertility Type that Is Most Suitable","volume":"38","author":"D Xie","year":"2018","journal-title":"Curr Med Sci"},{"key":"ref32","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1186\/1477-7827-10-67","article-title":"Balancing selected medication costs with total number of daily injections: a preference analysis of GnRH-agonist and antagonist protocols by IVF patients","volume":"10","author":"E S Sills","year":"2012","journal-title":"Reprod Biol Endocrinol"},{"key":"ref33","doi-asserted-by":"crossref","first-page":"k2644","DOI":"10.1136\/bmj.k2644","article-title":"Risks of ovarian, breast, and corpus uteri cancer in women treated with assisted reproductive technology in Great Britain, 1991\u20132010: data linkage study including 2.2 million person years of observation","volume":"362","author":"C L Williams","year":"2018","journal-title":"BMJ"},{"key":"ref34","doi-asserted-by":"crossref","first-page":"940","DOI":"10.1016\/j.fertnstert.2017.01.021","article-title":"Perinatal outcomes in children born after fresh or frozen embryo transfer: a Catalan cohort study based on 14,262 newborns","volume":"107","author":"M Vidal","year":"2017","journal-title":"Fertil Steril"},{"key":"ref35","doi-asserted-by":"crossref","first-page":"38","DOI":"10.4274\/jtgga.2016.0186","article-title":"Frozen embryo transfer prevents the detrimental effect of high estrogen on endometrium receptivity","volume":"18","author":"A Adeviye Ersahin","year":"2017","journal-title":"J Turk Ger Gynecol Assoc"},{"key":"ref36","doi-asserted-by":"crossref","first-page":"641","DOI":"10.1093\/biolre\/ioy187","article-title":"Effects of letrozole and clomiphene citrate on Wnt signaling pathway in endometrium of polycystic ovarian syndrome and healthy women","volume":"100","author":"S Mehdinejadiani","year":"2019","journal-title":"Biol Reprod"},{"key":"ref37","doi-asserted-by":"crossref","first-page":"775","DOI":"10.1080\/09513590.2018.1446934","article-title":"The effects of letrozole and clomiphene citrate on ligands expression of Wnt3, Wnt7a, and Wnt8b in proliferative endometrium of women with Polycystic ovarian syndrome","volume":"34","author":"S Mehdinejadiani","year":"2018","journal-title":"Gynecol Endocrinol"},{"key":"ref38","doi-asserted-by":"crossref","first-page":"1009","DOI":"10.1093\/humrep\/dex035","article-title":"Endometrial thickness in women undergoing IUI with ovarian stimulation. How thick is too thin? A systematic review and meta-analysis","volume":"32","author":"N S Weiss","year":"2017","journal-title":"Hum Reprod"},{"key":"ref39","doi-asserted-by":"crossref","first-page":"862","DOI":"10.1080\/09513590.2019.1612358","article-title":"Comparison of endometrial receptivity of clomiphene citrate versus letrozole in women with polycystic ovary syndrome: a randomized controlled study","volume":"35","author":"L Wang","year":"2019","journal-title":"Gynecol Endocrinol"},{"key":"ref40","doi-asserted-by":"crossref","first-page":"618","DOI":"10.1111\/jcpt.12831","article-title":"Impact of letrozole versus clomiphene citrate on endometrial receptivity in Iraqi women with polycystic ovarian syndrome","volume":"44","author":"M T Al-Obaidi","year":"2019","journal-title":"J Clin Pharm Ther"},{"key":"ref41","first-page":"134","article-title":"Clomiphene citrate vs. letrozole for cryopreserved-thawed embryo transfer: a randomized, controlled trial","volume":"55","author":"I Wagman","year":"2010","journal-title":"J Reprod Med"},{"key":"ref42","doi-asserted-by":"crossref","first-page":"82","DOI":"10.1016\/j.fertnstert.2005.01.117","article-title":"The aromatase inhibitor letrozole increases the concentration of intraovarian androgens and improves in vitro fertilization outcome in low responder patients: a pilot study","volume":"84","author":"J A Garcia-Velasco","year":"2005","journal-title":"Fertil Steril"},{"key":"ref43","doi-asserted-by":"crossref","first-page":"1325","DOI":"10.1016\/j.fertnstert.2003.03.001","article-title":"Effects of letrozole on superovulation with gonadotropins in women undergoing intrauterine insemination","volume":"80","author":"S Healey","year":"2003","journal-title":"Fertil Steril"},{"key":"ref44","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1111\/cen.13795","article-title":"Recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome","volume":"89","author":"H J Teede","year":"2018","journal-title":"Clin Endocrinol (Oxf)"},{"key":"ref45","doi-asserted-by":"crossref","first-page":"289","DOI":"10.1097\/GCO.0b013e32833beebf","article-title":"Letrozole for ovulation induction and controlled ovarian hyperstimulation","volume":"22","author":"E A Pritts","year":"2010","journal-title":"Curr Opin Obstet Gynecol"},{"key":"ref46","doi-asserted-by":"crossref","first-page":"93","DOI":"10.4103\/0974-1208.117166","article-title":"Current evidence supporting \u201cletrozole\u201d for ovulation induction","volume":"6","author":"S Kar","year":"2013","journal-title":"J Hum Reprod Sci"},{"key":"ref47","doi-asserted-by":"crossref","first-page":"1352","DOI":"10.1016\/j.fertnstert.2012.10.008","article-title":"A historical perspective of aromatase inhibitors for ovulation induction","volume":"98","author":"R F Casper","year":"2012","journal-title":"Fertil Steril"},{"key":"ref48","doi-asserted-by":"publisher","DOI":"10.1016\/j.beem.2018.10.002","article-title":"Pharmacology of medications used for ovarian stimulation","author":"A M Quaas","year":"2018","journal-title":"Best Pract Res Clin Endocrinol Metab"},{"key":"ref49","doi-asserted-by":"crossref","first-page":"1761","DOI":"10.1016\/j.fertnstert.2006.03.014","article-title":"Congenital malformations among 911 newborns conceived after infertility treatment with letrozole or clomiphene citrate","volume":"85","author":"T Tulandi","year":"2006","journal-title":"Fertil Steril"},{"key":"ref50","first-page":"125","article-title":"No increased risk of major congenital anomalies or adverse pregnancy or neonatal outcomes following letrozole use in assisted reproductive technology","volume":"32","author":"T Tatsumi","year":"2017","journal-title":"Hum Reprod"}],"container-title":["Geburtshilfe und Frauenheilkunde"],"original-title":[],"language":"de","link":[{"URL":"http:\/\/www.thieme-connect.de\/products\/ejournals\/pdf\/10.1055\/a-1202-2059.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,8,11]],"date-time":"2024-08-11T20:57:15Z","timestamp":1723409835000},"score":1,"resource":{"primary":{"URL":"http:\/\/www.thieme-connect.de\/DOI\/DOI?10.1055\/a-1202-2059"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,8]]},"references-count":47,"journal-issue":{"issue":"08","published-online":{"date-parts":[[2020,8,14]]},"published-print":{"date-parts":[[2020,8]]}},"URL":"https:\/\/doi.org\/10.1055\/a-1202-2059","relation":{},"ISSN":["0016-5751","1438-8804"],"issn-type":[{"value":"0016-5751","type":"print"},{"value":"1438-8804","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,8]]}}}