Exploring stress and depressive symptoms in pregnancy and the IL-1β, IL-6, and C-reactive protein pathway: Looking for possible biomarker targets.

Background: Individuals undergo significant stress throughout pregnancy and are at high risk for depressive symptoms. Elevated stress and depressive symptoms are associated with inflammatory processes and adverse maternal-infant outcomes. However, the biological processes associated with psychosocial outcomes and the maternal immune system remain unclear. As such, we aimed to examine associations among perceived stress, depressive symptoms, salivary IL-1β, IL-6, and CRP levels, and hair and salivary cortisol levels during the second and third trimesters of pregnancy. Methods: We conducted an ancillary study consisting of 37 pregnant individuals. Participants collected salivary samples and measures of perceived stress and depression at 17-19 weeks, 25-27 weeks, and 32-34 weeks gestation. We collected a one-time hair sample between 36 and 40 weeks. Provided salivary samples were used to detect changes in cortisol, IL-1β, IL-6, and CRP levels. Hair was used to detect changes in cortisol levels throughout pregnancy. Results: Elevated levels of perceived stress and depressive symptoms are associated with increased salivary CRP levels, respectively (p = 0.0142, p = 0.0008). Salivary and hair cortisol increased significantly throughout the second and third trimesters of pregnancy (p = 0.0004 and p < 0.0001). We also observed variations in IL-6 during pregnancy (p = 0.029) and significant increases between 25 and 27 weeks (p = 0.016). Conclusion: Salivary samples may provide a non-invasive measurement of alterations in cytokine and cortisol levels in pregnant individuals reporting elevated stress and depressive symptoms. These may be candidate biomarkers for mechanistic study possibly aiding providers in early detection of deleterious immunological processes which could result in adverse maternal-infant outcomes.