Reproduction may be tied to immune system-survival instincts


It may be that women’s reproductive function is tied to their immune status. Previous studies have discovered this is true about human males, but American Journal of Human Biology has published the first study to show it may affect women as well.

Energy expenditure tied to survival, then reproduction

An animal’s energy must be carefully allocated for survival, according to anthropology professor Kathryn Clancy, University of Illinois who led the research. The body’s first priority is maintenance, which ensures survival. This includes the immune system. Any resources left over go to sustaining reproductive abilities. Environmental stressors can lessen available resources and therefore lessen what is left for reproduction.

Testing hormones

The study looked at hormone levels of reproductive-aged, farm-working women. During harvest, when physical activity was at a peak, ovarian suppression was evident. Additionally, they tested urine samples for C-reactive protein (CRP), a marker of inflammation. “Depending on the other factors that you look at alongside it, CRP can tell you about immune function or it can tell you about psychosocial stress, because CRP has been correlated to both of those things in other populations,” Clancy said. When CRP is high, progesterone is low.

Inflammation and reproduction may be inter-related

It may be that inflammation suppresses ovarian hormones. The two systems may be intertwined. “One is that there is an internal mechanism, and this local inflammation drives higher levels of CRP, and that is what’s correlating with the lower progesterone,” she explained. “The other possibility is that there is an external stressor lie psychosocial or immune stress driving allocation to maintenance effort, which in turn is suppressing ovarian hormones.”

The trade-off

“From an anthropological perspective, these trade-offs are really important because the help us understand the timing of different life events: Why does someone hit puberty when they do, why do they begin reproducing when they do, why do they space babies the way they do?” Clancy stated.

Source: MedicalNewsToday


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