{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,29]],"date-time":"2025-12-29T10:48:00Z","timestamp":1767005280418,"version":"3.48.0"},"reference-count":64,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2025,11,21]],"date-time":"2025-11-21T00:00:00Z","timestamp":1763683200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["82101744"],"award-info":[{"award-number":["82101744"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100017700","name":"Henan Provincial Science and Technology Research Project","doi-asserted-by":"publisher","award":["LHGJ20200317"],"award-info":[{"award-number":["LHGJ20200317"]}],"id":[{"id":"10.13039\/501100017700","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Acta Obstet Gynecol Scand"],"published-print":{"date-parts":[[2026,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Embryo transfer at the blastocyst stage has become popular in assisted reproductive technology, but it is still a challenge for embryologists to select the embryos with the highest implantation potential. We aimed to investigate whether blastocyst development speed and blastocyst quality affect pregnancy and perinatal outcomes in single frozen\u2013thawed blastocyst transfer (SFBT) cycles.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Material and Methods<\/jats:title>\n                    <jats:p>We therefore conducted a meta\u2010analysis to compare the pregnancy and perinatal outcomes after day 5 versus day 6 SFBT. Pregnancy and perinatal outcomes of SFBT included HCG positive rate, clinical pregnancy rate (CPR), live birth rate (LBR), miscarriage rate (MR), multiple pregnancy rate (MPR), ongoing pregnancy rate (OPR), ectopic pregnancy rate (EPR), mean birth weight, low birth weight (LBW) rate, rate of macrosomia, mean gestational age at birth, preterm birth rate, birth defects rate, and sex ratio (female\/male).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      A total of 106\u2009316 participants were included in this meta\u2010analysis and were assigned to the D5 (\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u200966\u2009329) and D6 (\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u200939\u2009987) SFBT groups. Pooled analysis showed that the D5 SFBT group had a higher HCG positive rate (RR 1.24, 95% CI 1.14\u20131.34), CPR (RR 1.28, 95% CI 1.22\u20131.34), OPR (RR 1.36, 95% CI 1.21\u20131.53), LBR (RR 1.39, 95% CI 1.32\u20131.47), and a lower MR (RR 0.78, 95% CI 0.73\u20130.83) than the D6 SFBT group. No significant difference was observed between the D5 and D6 SFBT groups in other pregnancy and perinatal outcomes. Subgroup analysis comparing poor\u2010quality D5 blastocysts with high\u2010quality D6 blastocysts revealed no significant differences in most outcomes, except for a lower HCG positive rate (RR 0.92, 95% CI 0.87\u20130.97) and a higher rate of macrosomia (RR 2.13, 95% CI 1.05\u20134.31) in the poor\u2010quality D5 group.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>The findings suggested that transfer D5 blastocysts should be prioritized over D6 blastocysts in SFBT in clinical practice. Besides, poor\u2010quality D5 blastocysts and D6 high\u2010quality blastocysts exhibited comparable outcomes. Given the overall low quality of available evidence, the association between the pregnancy outcomes and blastocyst development speed requires further investigation.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1111\/aogs.70090","type":"journal-article","created":{"date-parts":[[2025,11,21]],"date-time":"2025-11-21T11:21:26Z","timestamp":1763724086000},"page":"50-69","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Pregnancy and perinatal outcomes after day 5 versus day 6 blastocyst\u2010stage embryo transfer: A systematic review and meta\u2010analysis"],"prefix":"10.1111","volume":"105","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6226-6555","authenticated-orcid":false,"given":"Wenhui","family":"Hou","sequence":"first","affiliation":[{"name":"Reproductive Medical Center, Henan Province Key Laboratory for Reproduction and Genetics The First Affiliated Hospital of Zhengzhou University  Zhengzhou Henan 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Province Key Laboratory for Reproduction and Genetics The First Affiliated Hospital of Zhengzhou University  Zhengzhou Henan China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiuli","family":"Fan","sequence":"additional","affiliation":[{"name":"Obstetric Department The First Affiliated Hospital of Zhengzhou University  Zhengzhou Henan China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Feifei","family":"Zhao","sequence":"additional","affiliation":[{"name":"Reproductive Medical Center, Henan Province Key Laboratory for Reproduction and Genetics The First Affiliated Hospital of Zhengzhou University  Zhengzhou Henan 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