The rate of inflammation increases in elderly individuals. This low-grade inflammation (inflammaging) is associated with many degenerative diseases, such as atherosclerosis, dementia, the frailty syndrome and even life expectancy.
A research conducted at the University of Tampere in Finland shows that the number of sons a woman bears is associated with higher plasma levels of one inflammation factor, the C-reactive protein or CRP. The research used data on 90-year-old or older women gathered in the Vitality 90+ study and found that the level of CRP increases according to the number of sons a woman has born. This association depended on hereditary factors as some individuals were shown to be more prone to elevated levels of CRP than others. The number of daughters did not correlate with the level of inflammation.
Low-grade inflammation in old age is a multifactorial phenomenon. This study was the first to demonstrate the association between the number of sons and inflammaging.
Previous studies have indicated that the number of sons is associated with the mother’s shorter life expectancy and that no such association exists in the case of daughters. It has been speculated that the reason might be a more demanding pregnancy or the different effect that daughters and sons have on the family.
This research showed that the association between the number of sons and low-grade inflammation in old age is evident even 70 years after the pregnancies. The results seem to indicate that the adverse effect of sons born is not limited to factors that are present during the pregnancy or social effects but that long-term biological effects are also at play. A possible explanation could be the fetal cells that enter the mother during pregnancy, which the mother’s immune system interprets as alien and tries to remove from the body.
The research results were published in the article Number of sons contributes to ageing-associated inflammation in Scientific Reports on 27 February 27, 2015.