Researchers aren’t sure why it happens, but they’ve found “statistically significant increased” mortality rates for men who received red blood cell transfusions from women who had ever been pregnant.
The Journal of the American Medical Association published a study of more than 31,000 people who received red blood cells from another person. Men had an increased mortality from all causes after getting a transfusion from an “ever-pregnant female donor.” Women who received blood from donors who had ever been pregnant did not have a statistically higher mortality rate.
There was no link to increased mortality from red blood cells by a woman who had never been pregnant.
JAMA reports further research is needed to determine the reason for the increase in mortality rates.