{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,24]],"date-time":"2026-10-24T01:24:54Z","timestamp":1792805094693,"version":"4.5.0"},"reference-count":35,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2022,6,13]],"date-time":"2022-06-13T00:00:00Z","timestamp":1655078400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Natural Science Foundation of China","award":["81873856"],"award-info":[{"award-number":["81873856"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"crossref"}]},{"name":"National Natural Science Foundation of China","award":["20191814"],"award-info":[{"award-number":["20191814"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"crossref"}]},{"name":"National Natural Science Foundation of China","award":["201940287"],"award-info":[{"award-number":["201940287"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"crossref"}]},{"name":"National Natural Science Foundation of China","award":["2018YFC1003000"],"award-info":[{"award-number":["2018YFC1003000"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"crossref"}]},{"name":"the \u201cTwo-hundred Talent\u201d","award":["81873856"],"award-info":[{"award-number":["81873856"]}]},{"name":"the \u201cTwo-hundred Talent\u201d","award":["20191814"],"award-info":[{"award-number":["20191814"]}]},{"name":"the \u201cTwo-hundred Talent\u201d","award":["201940287"],"award-info":[{"award-number":["201940287"]}]},{"name":"the \u201cTwo-hundred Talent\u201d","award":["2018YFC1003000"],"award-info":[{"award-number":["2018YFC1003000"]}]},{"name":"Shanghai Health and Family Planning Commission","award":["81873856"],"award-info":[{"award-number":["81873856"]}]},{"name":"Shanghai Health and Family Planning Commission","award":["20191814"],"award-info":[{"award-number":["20191814"]}]},{"name":"Shanghai Health and Family Planning Commission","award":["201940287"],"award-info":[{"award-number":["201940287"]}]},{"name":"Shanghai Health and Family Planning Commission","award":["2018YFC1003000"],"award-info":[{"award-number":["2018YFC1003000"]}]},{"name":"National Key R&amp;D Program of China","award":["81873856"],"award-info":[{"award-number":["81873856"]}]},{"name":"National Key R&amp;D Program of China","award":["20191814"],"award-info":[{"award-number":["20191814"]}]},{"name":"National Key R&amp;D Program of China","award":["201940287"],"award-info":[{"award-number":["201940287"]}]},{"name":"National Key R&amp;D Program of China","award":["2018YFC1003000"],"award-info":[{"award-number":["2018YFC1003000"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Ectopic pregnancy (EP) is increasingly found in women treated with in vitro fertilization and embryo transfer (IVF\u2013ET). With the development of the freeze-all policy in reproductive medicine, it is controversial whether frozen embryo transfer (FET) could reduce the rate of EP. In this single-center, large-sample retrospective study, we analyzed 16,048 human chorionic gonadotrophin (hCG)-positive patients who underwent fresh embryo transfer (ET) or FET cycles between January 2013 and March 2022. Throughout the study, the total EP rate was 2.09% (336\/16,048), 2.16% (82\/3803) in the ET group, and 2.07% (254\/12,245) in the FET group. After adjustment for age, infertility causes, and other confounding factors, logistic regression results showed no statistical difference in EP rates between FET and ET groups (odds ratio (OR) 0.93 (0.71\u20131.22), p &gt; 0.05). However, among the 3808 patients who underwent fresh ET cycles, the OR for EP was significantly lower in the long agonist protocol group than in the gonadotropin-releasing hormone antagonist (GnRH-ant) protocol group (OR 0.45 (0.22\u20130.93), p &lt; 0.05). Through a large retrospective study, we demonstrated a slightly lower EP rate in FET cycles than in fresh ET cycles, but there was no significant difference. The long agonist protocol in ET cycles had a significantly lower risk of EP than the GnRH-ant protocol.<\/jats:p>","DOI":"10.3390\/jcm11123386","type":"journal-article","created":{"date-parts":[[2022,6,13]],"date-time":"2022-06-13T22:00:38Z","timestamp":1655157638000},"page":"3386","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Differences in Ectopic Pregnancy Rates between Fresh and Frozen Embryo Transfer after In Vitro Fertilization: A Large Retrospective Study"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1864-5782","authenticated-orcid":false,"given":"Zhijie","family":"Hu","sequence":"first","affiliation":[{"name":"Department of Assisted Reproduction, Shanghai Ninth People\u2019s Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Rd, Shanghai 200011, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5120-6242","authenticated-orcid":false,"given":"Danjun","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Assisted Reproduction, Shanghai Ninth People\u2019s Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Rd, Shanghai 200011, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7635-4401","authenticated-orcid":false,"given":"Qiuju","family":"Chen","sequence":"additional","affiliation":[{"name":"Department of Assisted Reproduction, Shanghai Ninth People\u2019s Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Rd, Shanghai 200011, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Weiran","family":"Chai","sequence":"additional","affiliation":[{"name":"Department of Assisted Reproduction, Shanghai Ninth People\u2019s Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Rd, Shanghai 200011, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qifeng","family":"Lyu","sequence":"additional","affiliation":[{"name":"Department of Assisted Reproduction, Shanghai Ninth People\u2019s Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Rd, Shanghai 200011, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Renfei","family":"Cai","sequence":"additional","affiliation":[{"name":"Department of Assisted Reproduction, Shanghai Ninth People\u2019s Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Rd, Shanghai 200011, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yanping","family":"Kuang","sequence":"additional","affiliation":[{"name":"Department of Assisted Reproduction, Shanghai Ninth People\u2019s Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Rd, Shanghai 200011, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xuefeng","family":"Lu","sequence":"additional","affiliation":[{"name":"Department of Assisted Reproduction, Shanghai Ninth People\u2019s Hospital, Shanghai Jiaotong University School of Medicine, 639 Zhizaoju Rd, Shanghai 200011, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,6,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"199","DOI":"10.1093\/humrep\/10.1.199","article-title":"Analysis of the incidence and risk factors associated with ectopic pregnancy following in-vitro fertilization and embryo transfer","volume":"10","author":"Marcus","year":"1995","journal-title":"Hum. 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