Cells were found in the blood of the boys’ mothers that may be associated with longer life

Traces of pregnancy can remain in the body for decades. Now a Dane research suggests that these very traces may be associated with longer life.

The idea is almost too promising: male-derived cells left in the body from boy pregnancies could help a woman live longer.

Finnish assistant professor of genetic epidemiology Taru Tukiainen The University of Eastern Finland does not yet swallow the interpretation as such.

According to him, the observation may be true, but it is not yet known with enough certainty what it could be. The result does not seem to indicate a genuine biological cause and effect.

According to Tukiainen, it is a matter of chimerism. It means that an organism has two genes.

“The idea that microchimerism and the remnants of the Y chromosome in a woman’s body would be an advantage for later health is interesting, but this research still leaves many open questions,” says Tukiainen in an email.

In research was followed 766 women and 1,000 men who were between 50 and 64 years old at the start of the study.

Women were searched for so-called male microchimerism in their blood samples. It means Y-chromosome DNA from a male fetus or other source.

The researchers then tracked the participants’ mortality from national registries through 2017.

Male DNA was found in 71 percent of the women. In the study, their mortality was about half as low as that of women whose male DNA was not found.

When the researchers tried to take into account other factors affecting mortality, the association remained. These factors include, for example, smoking, alcohol use, body mass index, education, exercise, diet and number of births.

Major the difference was reflected in cancer mortality. Women who had male-derived cells in their blood died from cancer less often than women who did not.

According to Tukiainen, the phenomenon is biologically interesting. However, research does not yet show that male-derived cells themselves protect women from disease or death.

According to Tukiainen, it may be that the finding tells more about the woman’s general state of health or biological age than directly about the influence of the Y chromosome. Biological age tells whether the body is younger or older than its age.

“Male DNA can only be a sign of health and not the reason why some women live longer.”

In other words, male-derived DNA can only be a hint that the body is otherwise healthier, and not yet proof that these very cells extend life.

It would be good to confirm the results with larger data.

Supportive points out that if the phenomenon were directly caused by boy pregnancies, the connection should also be more clearly seen in whether mothers who give birth to many boys live longer.

If male microchimerism could be explained directly by male pregnancies, one could think that mothers who gave birth to many boys would live longer, at least because of that.

“We have looked a little at this idea in Finnish materials and we have not found a connection like this,” says Tukiainen.

For pregnancies and there are many other health risks and benefits associated with their timing. Therefore, ruling out all confounding factors is not straightforward.

The Danish researchers emphasize that their findings do not prove cause and effect. Male DNA can be a protective factor, but it can also tell about some other difference related to a woman’s health. The discovery is interesting, but does not yet explain why some women live longer than others.