Study Links Women’s Reproductive Function to their Immune Status

A new study conducted by researchers at the University of Illinois links women's reproductive function to their immune status. Previously, studies have found this relation in human males, but this is the first study to find the association in females.

The study was led by Kathryn Clancy, an anthropology professor from the University of Illinois. According to Clancy, the first priority of the body is maintenance, consisting of tasks inherently related to survival that includes immune function. The energy that is left out is then contributed to reproduction. A balance has to be maintained between the resources allocated to maintenance and reproductive efforts, and environmental stressors can reduce these available limited resources.

The study participants consisted of a group of healthy, premenopausal and rural Polish women who had taken part in traditional farming practices. For this study, researchers collected the women's urine and saliva samples during the harvest season, since during this time, physical activity levels are at their peak. Physical work is one of the factors that limits the available energetic resources. Previous studies have shown that the highest levels of ovarian suppression happened during the harvest season.

Researchers measured the participant's salivary ovarian hormone levels daily over one menstrual cycle. They also tested the levels of C-reactive protein (CRP) in urine samples, as this is a commonly used marker of inflammation.

A negative relation between CRP and progesterone was noticed among the participants: those with high CRP had low progesterone. The strongest predictors of CRP levels were estradiol and the age of first menstruation.

"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," Clancy said in a press statement. "The other possibility is that there is an external stressor like psychosocial or immune stress driving allocation to maintenance effort, which in turn is suppressing ovarian hormones."

With this study, the researcher hopes that women will be able to understand their bodies better. The details of the study appear in American Journal of Human Biology.