{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,13]],"date-time":"2026-07-13T10:32:29Z","timestamp":1783938749936,"version":"3.55.0"},"reference-count":29,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2025,8,18]],"date-time":"2025-08-18T00:00:00Z","timestamp":1755475200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003710","name":"Korea Health Industry Development Institute (KHIDI)","doi-asserted-by":"publisher","award":["RS-2025-02183084"],"award-info":[{"award-number":["RS-2025-02183084"]}],"id":[{"id":"10.13039\/501100003710","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Human chorionic gonadotropin (hCG) is a pregnancy biomarker, and five forms of this hormone are involved in female physiological regulation. \u03b2-core fragment hCG (bcf-hCG) is a fragment of hCG whose biological role in female reproduction has not been completely elucidated. This study aimed to investigate its role in embryo implantation and maintenance of a pregnancy-supportive environment. We analyzed the protein expression pattern of bcf-hCG in the intrauterine environment during early pregnancy by performing western blotting and immunohistochemistry with a monoclonal anti-bcf-hCG antibody. We performed a cell proliferation assay in the presence of bcf-hCG compared with intact hCG. We conducted an ex vivo study by performing intrauterine injection of bcf-hCG or intact hCG in mice. Endometrial thickness was measured using histological methods, and uterine gene and protein expression were analyzed following intrauterine injection of bcf-hCG. We evaluated the effect of bcf-hCG on embryo implantation in the uterus. bcf-hCG was highly abundant in the placenta and epithelial stromal glands of the uterine endometrium during early pregnancy and significantly induced proliferation of a stromal epithelial cell line. Intrauterine injection of bcf-hCG induced expression of specific genes and proteins, including homeobox A10, for embryo implantation and placental development. Upon embryo transfer, the implantation rate of bcf-hCG-treated embryos was higher than that of control embryos. In conclusion, bcf-hCG plays a role in the proliferation of glandular epithelial cells in the endometrium and placenta during early pregnancy. Therefore, bcf-hCG is an early-phase pregnancy biomarker that maintains the initial phase of pregnancy.<\/jats:p>","DOI":"10.3390\/ijms26167974","type":"journal-article","created":{"date-parts":[[2025,8,18]],"date-time":"2025-08-18T16:22:33Z","timestamp":1755534153000},"page":"7974","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["The Role of \u03b2-Core Fragment hCG in Embryo Implantation and Early Pregnancy"],"prefix":"10.3390","volume":"26","author":[{"given":"Ji Soo","family":"Ryu","sequence":"first","affiliation":[{"name":"Department of Biomedical Science, CHA University, Pocheon 13488, Gyeonggi-do, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1458-2262","authenticated-orcid":false,"given":"Nu Ri","family":"Yang","sequence":"additional","affiliation":[{"name":"CHA Fertility Center Seoul Station, Seoul 04637, Republic of Korea"},{"name":"Department of Obstetrics and Gynecology, Graduate School of Medicine, CHA University, Pocheon 13488, Gyeonggi-do, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yu Ha","family":"Shim","sequence":"additional","affiliation":[{"name":"Department of Biomedical Science, CHA University, Pocheon 13488, Gyeonggi-do, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yu Jin","family":"Kim","sequence":"additional","affiliation":[{"name":"CHA Fertility Center Seoul Station, Seoul 04637, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Won Jae","family":"Kwag","sequence":"additional","affiliation":[{"name":"R&D Center, ADTech Co. Ltd., Gunpo-si 15845, Gyeonggi-do, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jin Dong","family":"Chang","sequence":"additional","affiliation":[{"name":"R&D Center, ADTech Co. Ltd., Gunpo-si 15845, Gyeonggi-do, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8735-444X","authenticated-orcid":false,"given":"Jae Ho","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Biomedical Science, CHA University, Pocheon 13488, Gyeonggi-do, Republic of Korea"},{"name":"CHA Fertility Center Seoul Station, Seoul 04637, Republic of Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,8,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"D\u2019Hauterive, S.P., Close, R., Gridelet, V., Mawet, M., Nisolle, M., and Geenen, V. (2022). 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