{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,7]],"date-time":"2026-11-07T01:14:31Z","timestamp":1794014071376,"version":"4.8.0"},"reference-count":21,"publisher":"FapUNIFESP (SciELO)","issue":"9","license":[{"start":{"date-parts":[[2025,1,1]],"date-time":"2025-01-01T00:00:00Z","timestamp":1735689600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2025,1,1]],"date-time":"2025-01-01T00:00:00Z","timestamp":1735689600000},"content-version":"am","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2025,1,1]],"date-time":"2025-01-01T00:00:00Z","timestamp":1735689600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Rev. Assoc. Med. Bras."],"abstract":"<jats:p>SUMMARY  OBJECTIVE: Low kisspeptin levels are observed in those with reproductive difficulties. This study was designed to examine and compare kisspeptin levels in women with infertility and miscarriages. Moreover, the aim of this study was to evaluate the possible relationship between kisspeptin levels and the C677T and A1298C polymorphisms of the methylenetetrahydrofolate reductase gene, as well as certain biochemical parameters in these two groups.  METHODS: A total of 76 women, including 46 infertile women and 30 women with a history of miscarriages, were included in the study. In addition to kisspeptin levels, thyroid-stimulating hormone, free triiodothyronine, free thyroxine, ferritin, vitamin B12, folate, prolactin, and homocysteine levels were analyzed in individuals in both groups. The distribution of the C677T and A1298C polymorphisms of the methylenetetrahydrofolate reductase gene was also evaluated.  RESULTS: Women with infertility had lower kisspeptin levels (p=0.019, Cohen's d=0.62) and higher vitamin B12 levels (p=0.018, Cohen's d=0.50) than women with miscarriages. Thyroid-stimulating hormone, free triiodothyronine, free thyroxine, ferritin, folate, prolactin, and homocysteine levels were not different between the two groups. There was no difference in the genotype distribution of methylenetetrahydrofolate reductase C677T and A1298C gene polymorphisms between the groups. There was no correlation between kisspeptin levels and other parameters in both groups. No difference was found between kisspeptin levels of individuals with different methylenetetrahydrofolate reductase C677T and A1298C gene polymorphism genotypes.  CONCLUSION: Kisspeptin levels were lower in women with infertility compared to women with a history of miscarriages, suggesting a possible association between low kisspeptin levels and reproductive difficulties and warranting further investigation.<\/jats:p>","DOI":"10.1590\/1806-9282.20250716","type":"journal-article","created":{"date-parts":[[2025,10,17]],"date-time":"2025-10-17T15:04:56Z","timestamp":1760713496000},"source":"Crossref","is-referenced-by-count":1,"title":["Kisspeptin levels in infertile and miscarried women: a cross-sectional study on the relationship with methylenetetrahydrofolate reductase gene polymorphisms and biochemical parameters"],"prefix":"10.1590","volume":"71","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1921-2583","authenticated-orcid":false,"given":"Adem","family":"Keskin","sequence":"first","affiliation":[{"name":"Ayd\u0131n Adnan Menderes University,  Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9763-7643","authenticated-orcid":false,"given":"Naim","family":"Uzun","sequence":"additional","affiliation":[{"name":"A\u011fr\u0131 \u0130brahim \u00c7e\u00e7en University,  Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1517-3356","authenticated-orcid":false,"given":"Recai","family":"Aci","sequence":"additional","affiliation":[{"name":"Ayd\u0131n Adnan Menderes University,  Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0025-8717","authenticated-orcid":false,"given":"Melek","family":"Bilgin","sequence":"additional","affiliation":[{"name":"Samsun University,  Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3437-5324","authenticated-orcid":false,"given":"Taner","family":"Karakaya","sequence":"additional","affiliation":[{"name":"Samsun University,  Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5727-7965","authenticated-orcid":false,"given":"Ozlem","family":"Sezer","sequence":"additional","affiliation":[{"name":"Samsun University,  Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3764-1659","authenticated-orcid":false,"given":"Samet","family":"Semiz","sequence":"additional","affiliation":[{"name":"Ondokuz May\u0131s University,  Turkey"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"530","published-online":{"date-parts":[[2025]]},"reference":[{"issue":"1","key":"ref1","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1001\/jama.2021.4788","article-title":"Diagnosis and management of infertility: a review","volume":"326","author":"Carson SA","year":"2021","journal-title":"JAMA"},{"key":"ref2","series-title":"Reproductive hormones","volume-title":"Kisspeptin: role in female infertility [Internet]","author":"K\u00fck\u00fcrt A","year":"2021"},{"issue":"1","key":"ref3","doi-asserted-by":"crossref","first-page":"5","DOI":"10.3390\/biomedicines7010005","article-title":"Hypothalamic-pituitary-ovarian axis disorders impacting female fertility","volume":"7","author":"Mikhael S","year":"2019","journal-title":"Biomedicines"},{"issue":"10285","key":"ref4","doi-asserted-by":"crossref","first-page":"1658","DOI":"10.1016\/S0140-6736(21)00682-6","article-title":"Miscarriage matters: the 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