Yoga Reduces Stress and Improves Immunity during Pregnancy

Author: Lauren Frick

A randomized controlled trial tested the effects of prenatal yoga on women’s stress and immune function during various stages of pregnancy. Stress is known to have adverse effects on both mother and baby during pregnancy. With stress, the body produces more cortisol which ultimately decreases immunity to viruses and pathogens and hinders the release of immunoglobulin A (IgA). Cortisol and IgA are biomarkers that indicate women’s stress and immunity levels. When the body is stressed, the hypothalamus produces corticotropin-releasing factor, which leads to the production of adrenocorticotropin, which causes adrenal secretion of cortisol. In addition to this increased amount of cortisol being in the body, the placenta also produces the releasing factor that leads to the secretion of adrenal cortisol during pregnancy. It is important to regulate the amount of cortisol that is in the body, and pharmaceuticals often pose risks for the fetus. Thus, utilizing complementary medicine like yoga can help to naturally decrease the amount of cortisol released. 

Yoga has been found to decrease stress when practiced, and in turn reduces the amount of cortisol released. It has also been found to improve birth outcomes and ease labor pains and anxieties. The researchers who conducted this study hypothesized that pregnant women who practice yoga will have decreased salivary cortisol levels and higher salivary IgA levels than women who did not do yoga during pregnancy.

101 women took part in this study, 50 of which were assigned to practice yoga and 51 only partook in standard prenatal care. The women attended yoga classes catered to women who were in their second and third trimesters twice a week for 20 weeks. The classes included “stretching, deep breathing, guided imagery, and deep relaxation” (P.J. Chen et al., 2017, 111). Prior to the class, saliva samples were taken from the women, and the same was done after the class. This was done in order to compare the levels of cortisol and IgA before and after yoga. 

The researchers found that directly after practicing yoga, the women’s salivary cortisol levels decreased while their IgA levels increased. This means that their stress was reduced after yoga. They also found that yoga had a long-term effect on increasing IgA levels at 36 weeks compared to the women who did not practice yoga. There was not a long-term effect found between yoga and salivary cortisol levels, perhaps because cortisol levels are subject to change considering that seasonal changes, mood, and sleep can easily influence them. It was also found that the women who practices yoga birthed babies with higher birth weights. This may be related to the fact that “yoga [relaxes] uterine arteries and [increases] blood flow to the uterus,” thus leading to a healthier baby.  

It can be concluded that consistent practice of yoga throughout pregnancy can decrease stress and increase immune function. While the decrease of cortisol levels associated with stress is only influenced short-term, it still reduces the amount of cortisol in the body which leads to more IgA in the long run. With an increase in IgA, women will have stronger immune function throughout pregnancy. Thus, yoga can be utilized as a method to reduce stress during pregnancy and hopefully reduce the chance of health issues with both mother and baby. 


Chen, P.-J., Yang, L., Chou, C.-C., Li, C.-C., Chang, Y.-C., & Liaw, J.-J. (2017). Effects of prenatal yoga on women’s stress and immune function across pregnancy: A randomized controlled trial. Complementary Therapies in Medicine31, 109–117.