A study suggests that men who receive blood transfusions from women who have previously been pregnant may face a higher risk of death, although the underlying reason remains unclear.
The Dutch study examined more than 30,000 patients who received nearly 60,000 blood transfusions. Researchers analyzed whether the sex and pregnancy history of blood donors affected patient outcomes.
The results showed a noticeable difference in mortality rates depending on the donor. Male patients who received blood from women who had previously been pregnant experienced higher mortality compared with those who received blood from male donors or from women who had never been pregnant.
Specifically, transfusions from previously pregnant women were associated with about 101 deaths per 1,000 male recipients per year. In comparison, transfusions from male donors were linked to approximately 80 deaths per 1,000 recipients annually. No similar increase in risk was observed when the blood came from women who had never been pregnant.
“Male recipients who received a transfusion from an ever-pregnant female donor had a statistically significant increase in mortality compared with those who received a transfusion from a male donor or from a female donor without a history of pregnancy,” wrote Dr. Rutger Middelburg in the Journal of the American Medical Association.
One possible explanation involves antibodies that develop during pregnancy. These antibodies help protect the fetus but may influence immune responses in transfusion recipients.
“The association of increased mortality among male patients who received transfusions from ever-pregnant donors suggests a possible mechanism based on immunologic changes occurring during pregnancy,” Middelburg noted.
Another potential explanation could involve biological differences between male and female donors, such as variations in iron levels or differences in red blood cell physiology.
The researchers emphasize that more studies are needed to confirm the findings, understand their clinical significance, and identify the biological mechanisms behind the observed association.
If confirmed, the findings could influence future transfusion practices, potentially encouraging healthcare providers to consider donor pregnancy history when selecting blood for male patients.
Reference:
Caram-Deelder, C. 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, October 17, 2017; 318(15):1471–1478. DOI: 10.1001/jama.2017.14825.