{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,22]],"date-time":"2026-10-22T15:12:05Z","timestamp":1792681925106,"version":"4.5.0"},"reference-count":24,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T00:00:00Z","timestamp":1784246400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Med."],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>\n                      Preservation of fertility for women of reproductive age with malignant ovarian tumors is a complex issue, as organ-preserving treatment may increase the risk of recurrence. Direct involvement of the ovary in the tumor process significantly limits the possibility of implementing the most effective methods: the stimulation of ovulation and cryopreservation of ovarian tissue due to the risk of contamination by tumor cells. The only possible method of preserving fertility in such cases may be the OTO-IVM (Ovarian tissue oocyte\n                      <jats:italic>in vitro<\/jats:italic>\n                      maturation) method. It is based on obtaining immature oocytes from tissue of ovary removed during surgical treatment and their subsequent maturation in vitro. Up to date, based on the literature, 6 children have been born using this method (in three cases, the female patients had an ovarian tumor). In all cases, embryos were transferred at the cleavage stage.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We present the first case of a successful birth as a result of the implementation of the OTO-IVM fertility preservation program with embryo transfer performed at the blastocyst stage. A 29-year-old female patient with a recurrence of a borderline tumor in a single ovary underwent surgery to preserve the uterus and remove the tumor-affected ovary.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Findings<\/jats:title>\n                    <jats:p>22 cumulus-oocyte complexes were retrieved from the removed ovary. As a result of OTO-IVM, 12 metaphase II stage oocytes were obtained, which were fertilized using the intracytoplasmic sperm injection (ICSI) method; 3 blastocyst stage embryos were obtained and cryopreserved. The female patient was prescribed cyclic hormone replacement therapy. After 9 months, one embryo was thawed and transferred into the uterine cavity, resulting in clinical pregnancy. Normal delivery by way of natural maternal passages, a healthy boy was born at the term of 37 weeks and 6 days.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>Our work confirms that the OTO-IVM method has high value for preserving fertility in female patients with malignant ovarian tumor. We have shown for the first time that prolonged cultivation of embryos to the blastocyst stage in OTO-IVM programs can lead to live birth. Cultivation to the blastocyst stage makes it possible to conduct preimplantation testing of embryos, which is extremely important for patients with genetically determined forms of cancer. It is necessary to continue research to improve the method and determine the indications and contraindications for its implementation.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fmed.2026.1857432","type":"journal-article","created":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T05:43:07Z","timestamp":1784266987000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Clinical case: successful birth as a result of the transfer of an embryo at the blastocyst stage from an oocyte obtained from a tumoral ovary using the OTO-IVM method"],"prefix":"10.3389","volume":"13","author":[{"given":"Yuliya","family":"Tatishcheva","sequence":"first","affiliation":[{"name":"Department of Obstetrics and Gynecology, N.N. Petrov National Medical Research Oncology Center","place":["Saint Petersburg, Russia"]},{"name":"Reproductive Medicine Clinic, Skyfert Ltd.","place":["Saint Petersburg, Russia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Olga","family":"Lavrinovich","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, N.N. Petrov National Medical Research Oncology Center","place":["Saint Petersburg, Russia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dmitri","family":"Gerkulov","sequence":"additional","affiliation":[{"name":"Reproductive Medicine Clinic, Skyfert Ltd.","place":["Saint Petersburg, Russia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alla","family":"Kalugina","sequence":"additional","affiliation":[{"name":"Reproductive Medicine Clinic, Skyfert Ltd.","place":["Saint Petersburg, Russia"]},{"name":"Department of Obstetrics- Gynecology and Neonatology, I.P. 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