Mortality After Transfusion of Ever-pregnant donor Red blood cells


In 2011, a link between donor sex and death of transfusion recipients was observed in red blood cell transfusions1. This was further investigated by Caram-Deelder et al., who showed the transfusion of red blood cells from ever-pregnant donors was associated with higher mortality in young men (with age up to 50 years).2 However, the biological mechanisms explaining this association remained unclear. More data is needed to be able to specify which combination of characteristics of both donors and patients determines this increased risk of mortality after red blood cell transfusions.

Therefore, the MATER study was initiated: ‘Mortality After Transfusion of Ever-pregnant donor Red blood cells’. Here, we aim to validate previous research on the association between donor pregnancy history and transfusion recipient mortality.


Red blood cells constitute the biggest part of the blood supply. They are currently transfused without consideration of the sex of the blood donor and the recipient. Recent evidence shows such a policy to be associated with increased mortality in male recipients of red blood cells from female donors with a history of pregnancy.2 This project aims to find clues for the biological mechanism behind this association. This knowledge will allow for more personalized future transfusion strategies that will minimize both side effects and associated mortality of recipients of red blood cell transfusions.


First-ever transfusion recipients in the Netherlands between 2005 and 2019 which were performed in the hospitals participating in the R-FACT study will be included in this study. All blood donations and the corresponding donors linked to these recipients will be included in this study. Cox regression analysis will be used to assess the effect of donor pregnancy on transfusion recipient mortality. This analysis method allows modelling the relation between exposure (donor pregnancy history), outcome (mortality), and confounders (e.g. total number of transfusions, year of transfusion, ABO and Rh blood type, sex of the patient, and hospital) taking into account that exposure and confounders vary over time.

Pregnancy history will be investigated as number of pregnancies, time since last pregnancy, different partners and type of pregnancy (i.e. boy versus girl pregnancies, outcome of pregnancy). The hazard ratio  will be presented for exposure to blood products with different characteristics, stratified by patient age, sex and (if possible) transfusion indication. Effect modification by storage time will also be investigated.


Research Staff 



  1. Center for Clinical Transfusion Research, Sanquin Research, Leiden, The Netherlands 
  2. Jon J van Rood Center for Clinical Transfusion Research, Sanquin-Leiden University Medical Center, Leiden
  3. Department of Clinical Epidemiology, Leiden University Medical Center, Leiden
  4. Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden
  5. Department of Haematology, Radboudumc, Nijmegen
  6. LabWest, Haga Teaching Hospital, The Hague
  7. Department of Clinical Chemistry and Haematology, Catharina Hospital, Eindhoven
  8. Department of Clinical Chemistry and Haematology, Jeroen Bosch Hospital, ‘s Hertogenbosch
  9. Department of Clinical Chemistry and Haematology, University Medical Center Utrecht, Utrecht
  10. Department of Haematology, Amsterdam UMC, location VUmc, Amsterdam


1.Middelburg RA, Briet E, van der Bom JG. Mortality after transfusions, relation to donor sex. Vox sanguinis 2011;101:221-9. Abstract

2. Caram-Deelder C, Kreuger AL, Evers D, et al. Association of Blood Transfusion From Female Donors With and Without a History of Pregnancy With Mortality Among Male and Female Transfusion Recipients. Jama 2017;318:1471-8. Abstract