Official Journal of the British Blood Transfusion Society Transfusion Medicine | REVIEW ARTICLE Approaches to understanding and interpreting the risks of red blood cell transfusion in neonates A. K. Keir, 1,2 H. New, 3,4 N. Robitaille, 5 G. L. Crighton, 6,7 E. M. Wood 7 & S. J. Stanworth 8,9 1 Healthy Mothers, Babies and Children, e South Australian Medical and Research Institute, North Adelaide, South Australia, Australia, 2 Robinson Research Institute and the Adelaide Medical School, e University of Adelaide, Adelaide, South Australia, Australia, 3 NHS Blood and Transplant, London, UK, 4 Imperial College London, London, UK, 5 Division of Hematology–Oncology, Department of Pediatrics, CHU Sainte-Justine, Montréal, Quebec, Canada, 6 Department of Haematology, Royal Children’s Hospital, Melbourne, Victoria, Australia, 7 Transfusion Research Unit, Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia, 8 NHS Blood and Transplant and Department of Haematology, Oxford University Hospitals NHS Foundation Trust, Oxford, UK, and 9 Radcliffe Department of Medicine, University of Oxford, Oxford, UK Received 7 September 2018; accepted for publication 13 December 2018 SUMMARY In this review, we explore how to assess potential harm related to neonatal transfusion practice. We consider different sources of information, including passive or active surveillance sys- tems such as registries, observational studies, randomised trials and systematic reviews. Future research directions are discussed. Key words: adverse effects, haemovigilance, infants. Transfusions are given therapeutically to treat a clinical prob- lem, such as giving red cells to improve oxygen delivery, or prophylactically to prevent a problem, such as platelets to prevent bleeding. ere is uncertain evidence in many cases. erefore, the balance between perceived benefit and risk of harm needs to be carefully considered. Neonates, especially preterm low-birth-weight (LBW) infants, are an immunologi- cally immature, highly transfused patient population that may receive large transfusion volumes relative to their total blood volume. For this group of patients, it is particularly important to have a clear understanding of both potential immediate harms and long-term consequences given the expectation of their post-transfusion survival over many decades. Neonatal adverse transfusion reactions remain particularly poorly characterised. ey may be difficult to distinguish from is review is based in part on an invited presentation by S. S. at the International Haemovigilance Seminar, held in Manchester, UK, July 2018. Correspondence: Dr. Amy Keir, Neonatal Department, Women’s and Children’s Hospital, North Adelaide, SA 5006, Australia. Tel.: +61 8 8161 7631; fax: +61 8 8161 7654; e-mail: amy.keir@adelaide.edu.au non-specific changes or a worsening of concurrent clinical morbidities, such as hypoxia, apnoeic episodes, requirement for increased respiratory support, rash or fever. Oxygen require- ments and the degree of respiratory support are important indicators that guide red blood cell (RBC) transfusions in neonates. Yet worsening hypoxia, apnoea or increased respira- tory requirements in an extremely preterm infant with chronic lung disease (CLD) receiving an RBC transfusion for anaemia of prematurity (AOP) may be the earliest indicators of an adverse transfusion reaction and may be unrecognised and unreported as an transfusion adverse event. Neonates are at particular risk of metabolic complications such as hypocalcaemia, hyper- kalaemia, hypothermia and overload conditions if large-volume transfusions are given rapidly with insufficient monitoring. is review explores how we can identify and assess harm related to the practice of neonatal transfusion medicine. We will consider different sources of information, including passive or active surveillance systems such as registries, observational studies, randomised trials and systematic reviews. NEONATAL MEDICINE ere have been major changes in the characteristics and types of admissions to neonatal units over the last few decades. Infants born at 27 or 28 weeks’ gestation, an age that 20 years ago would have been considered to be at the limits of medical care, are now admitted with an expectation of discharge home. e EPICure studies found increases in survival for extremely preterm babies (22–26 weeks’ gestation) from 40% in 1995 to 53% in 2006. Of note, no differences in rates of neonatal morbidities (findings on cerebral ultrasonography, bronchopulmonary dysplasia, retinopathy of prematurity or surgically treated necrotising enterocolitis) were reported, despite advances in neonatal care over this time (Costeloe et al., 2012). is likely reflects © 2019 The Authors. Transfusion Medicine published by John Wiley & Sons Ltd on behalf of British Blood Transfusion Society doi: 10.1111/tme.12575 This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.