{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,16]],"date-time":"2026-02-16T18:28:02Z","timestamp":1771266482489,"version":"3.50.1"},"reference-count":18,"publisher":"Wiley","issue":"9","license":[{"start":{"date-parts":[[2025,7,14]],"date-time":"2025-07-14T00:00:00Z","timestamp":1752451200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Transfusion"],"published-print":{"date-parts":[[2025,9]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>Maternal alloantibody formation against fetal blood cell antigens can lead to hemolytic disease of the fetus and newborn (HDFN), and anti\u2010K alloimmunization has the potential to result in severe HDFN. Despite the benefits of prophylactic K\u2010matched red blood cell transfusions demonstrated in other high\u2010income countries, the United States lacks such a national policy for patients with pregnancy potential (PWPP). This study aims to characterize a population of PWPP impacted by anti\u2010K alloimmunization in a large US academic medical system.<\/jats:p><\/jats:sec><jats:sec><jats:title>Study Design and Methods<\/jats:title><jats:p>Retrospective review was undertaken to identify all cases of anti\u2010K alloimmunization among PWPP between August 1, 2021, and July 31, 2024, in the University of California, San Francisco (UCSF) network. Demographic, clinical, and transfusion data were collected from electronic medical records and the blood bank information system and reviewed by an interdisciplinary physician team.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Over the 3\u2010year study period, 150 anti\u2010K results were reported for 69 unique PWPPs. The median age was 38\u2009years (range: 11\u201350). Most PWPPs were not chronically transfused (32\/39; 82% with \u22646 lifetime RBC units) and lacked identifiable\u00a0alloimmunization\u2010associated comorbidities (45\/69; 65%). Thirty\u2010seven (63%) of the PWPPs had red blood cell transfusions administered only at facilities outside of the UCSF network. Five of fifteen (33%) pregnancies following incident anti\u2010K alloantibody identification resulted in healthy live births.<\/jats:p><\/jats:sec><jats:sec><jats:title>Discussion<\/jats:title><jats:p>Our results support reconsideration of a national policy of prophylactic K\u2010matching or K\u2010negative transfusion for people with pregnancy potential as a way to prevent further alloimmunization and improve clinical care in this population.<\/jats:p><\/jats:sec>","DOI":"10.1111\/trf.18333","type":"journal-article","created":{"date-parts":[[2025,7,14]],"date-time":"2025-07-14T10:24:27Z","timestamp":1752488667000},"page":"1567-1573","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Characterization of a population with pregnancy potential and anti\u2010<scp>K<\/scp> alloimmunization in the United States"],"prefix":"10.1111","volume":"65","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2986-0285","authenticated-orcid":false,"given":"Emily","family":"Kelly","sequence":"first","affiliation":[{"name":"Department of Laboratory Medicine University of California San Francisco  San Francisco California USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Marci","family":"Rosenberg","sequence":"additional","affiliation":[{"name":"School of Medicine University of California San Francisco  San Francisco California USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Juan","family":"Gonzalez\u2010Velez","sequence":"additional","affiliation":[{"name":"Department of Obstetrics, Gynecology and Reproductive Sciences University of California San Francisco  San Francisco California USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7896-2459","authenticated-orcid":false,"given":"Sara","family":"Bakhtary","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine University of California San Francisco  San Francisco California USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1034-2496","authenticated-orcid":false,"given":"Gisela","family":"Marrero\u2010Rivera","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine University of California San Francisco  San Francisco California USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2025,7,14]]},"reference":[{"key":"e_1_2_7_2_1","first-page":"1","article-title":"Cause\u2010of\u2010death data from the fetal death file, 2015\u20132017","volume":"69","author":"Hoyert DL","year":"2020","journal-title":"Natl Vital Stat Rep"},{"key":"e_1_2_7_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/S2352-3026(16)30019-9"},{"key":"e_1_2_7_4_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41372-023-01785-3"},{"key":"e_1_2_7_5_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1471-0528.2008.01984.x"},{"key":"e_1_2_7_6_1","doi-asserted-by":"publisher","DOI":"10.1111\/trf.13151"},{"key":"e_1_2_7_7_1","first-page":"528","article-title":"Relationship between previous maternal transfusions and haemolytic disease of the foetus and newborn mediated by non\u2010RhD antibodies","volume":"11","author":"Dajak S","year":"2013","journal-title":"Blood Transfus"},{"key":"e_1_2_7_8_1","doi-asserted-by":"publisher","DOI":"10.1111\/trf.16276"},{"key":"e_1_2_7_9_1","doi-asserted-by":"publisher","DOI":"10.1016\/S2352-3026(16)30043-6"},{"key":"e_1_2_7_10_1","doi-asserted-by":"publisher","DOI":"10.1097\/AOG.0000000000005701"},{"key":"e_1_2_7_11_1","doi-asserted-by":"publisher","DOI":"10.1111\/trf.12814"},{"key":"e_1_2_7_12_1","doi-asserted-by":"publisher","DOI":"10.1111\/trf.13977"},{"key":"e_1_2_7_13_1","unstructured":"The University of California SF.UCSF Enterprise Dashboards: Patient Demographics [Monograph on the Internet]. 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