Previously pregnant donor may up death risk in men

The most common cause of transfusion-related mortality is transfusion-related acute lung injury (TRALI), which is associated specifically with transfusions from female donors with a history of pregnancy, the researchers showed.

Women who receive blood transfusions from another woman who was pregnant in the past may not be at risk, the researchers observed, in the paper published by the journal JAMA.

"Male patients who received red blood cell transfusions, receipt of a transfusion from an ever-pregnant female donor was associated with a statistically significant increase in all-cause mortality among male recipients of red blood cell transfusions, but not among female recipients," said Rutger A. Middelburg, from the Sanquin Research in the Netherlands.

"The association suggests a possible mechanism based on immunologic changes occurring during pregnancy," Middelburg was quoted as telling Telegraph.

"An alternative explanation could be a difference in iron status between ever-pregnant female and male donors. Some studies also report differences in red blood cell physiology between the sexes," Middelburg noted.

For the study, the team analysed 31,118 patients who received 59,320 red blood cell transfusions from one of three types of donors (88 per cent male; 6 per cent ever-pregnant female; and 6 per cent never-pregnant female).

In total, 3,969 patients (13 percent mortality) died after being given blood.

There were 101 deaths after transfusion from an ever-pregnant donor compared with 80 after receiving blood from a male donor, per 1,000 person-years.

Female donors who had never been pregnant were associated with only 78 male deaths per 1,000 person-years.

"Further research is needed to replicate these findings, determine their clinical significance, and identify the underlying mechanism," the researchers said.