Second report of registry of the International Society of Uterus Transplantation (ISUTx): international activities 2000-2024.

study questionWhat have been the activities, characteristics, and outcomes of uterus transplantation (UTx) performed worldwide from 2000 through 2024? SUMMARY ANSWER: In 91 UTx cases, 67 involved live donors and 80 of the recipients had Mayer-Rokitansky-Küster-Hauser syndrome, with 12-month graft survival of 74%, enabling pregnancy attempts that yielded 44 healthy singleton deliveries with a live birth rate per embryo transfer of 30.3%. WHAT IS KNOWN ALREADY: UTx is the only treatment for women with absolute uterine factor infertility who wish to carry a pregnancy. According to a comprehensive report including data up to 2020 on 45 UTx cases, 19 live births occurred (35.8% per embryo transfer) at a mean of 35.3 weeks gestation. STUDY DESIGN, SIZE, DURATION: Data were extracted from the web-based registry of the International Society of Uterus Transplantation (ISUTx). This registry captures information on donor and recipient characteristics, transplantation procedures, postoperative complications, immunosuppression, complications including rejections, and reproductive outcome. Analyses were undertaken of the 91 transplants performed between 6 April 2000 and 31 December 2024, that were recorded in the registry. PARTICIPANTS/MATERIALS, SETTING,

methodsTwenty-four medical centers in five continents registered their uterus transplants by entering data from the day of transplantation until 3 months after graft removal. The following variables were assessed: the demographic and laboratory characteristics of donors and recipients, the source of graft (live versus deceased donor), surgical specifics including technique, duration, ischemic times, and post-op complications, immunosuppression, rejection data, pregnancy with live birth(s), and hysterectomy. MAIN RESULTS AND THE ROLE OF CHANCE: In 91 uterus transplantations (67 from live donors, 24 from deceased donors), the overall surgical success rate, defined as graft viability by 12 months, was 75%. Most recipients (88%) had Mayer-Rokitansky-Küster-Hauser syndrome, with mothers being the most frequent (64%) live donors. Live donor hysterectomies were performed by laparotomy (54%), robotics (28%), or laparoscopy (18%). Total ischemic time was shorter in live- versus deceased-donor UTx procedures. Rejection episodes that were treated with escalations of immunosuppression were more frequent during months 1-5 (44%) than during months 6-10 (28%) post-UTx. Graft survival during the first 12 months was superior when grafts from premenopausal donors were used as compared to from postmenopausal donors. Forty-four singleton live births (mean gestational length of 34.5 weeks), including eight second births, were reported, with a live birth rate per embryo transfer of 30%. Preeclampsia was the most common pregnancy complication, occurring in 23% of live-birth pregnancies. Major postnatal complications occurred in 11 infants, 9 with respiratory distress syndrome; no major malformations were observed. LIMITATIONS, REASONS FOR CAUTION: Data in the registry are self-reported and not subjected to validation. Although the ISUTx registry represents the most comprehensive quality registry of UTx activity in the world, cases from at least four centers are excluded as they were not entered into the registry. Birth outcomes from some registry cases are as yet unknown as these ongoing cases have not yet reached the endpoint of hysterectomy. WIDER IMPLICATIONS OF THE

findingsThis study presents the most comprehensive analysis to date of UTx, the only fertility treatment for absolute uterine factor infertility. The registry serves as the prime source for quality assessment and process improvement in UTx. STUDY FUNDING/COMPETING INTEREST(S): The establishment and operation of the registry were funded by the Swedish Research Council (2024-03487 to M.B.) and Jane and Dan Olsson Foundation (2024-11 to M.B.). There was no competing interest. TRIAL REGISTRATION NUMBER: Not applicable.