Does prenatal stress affect fetal development?

We can’t escape it -stress is a part of our everyday lives. From sitting in traffic, meeting a deadline, planning a wedding or listening to politicians, we all experience some degree of stress whether it is a good or bad.

However, it is how we cope with it that makes all the difference. In small amounts, stress can be advantageous by giving us that boost of energy needed to accomplish daily tasks and challenges.  

Stress also helps us to stave off dangerous situations by producing the fight-or-flight response; the perception of a threatening event triggers a release of catecholamines, epinephrine and norepinephrine and the stress hormone cortisol, which causes an increase in heart rate, blood pressure and blood flow to the muscles to meet the demands of survival. 

Stress can be lifesaving, but too much of it can be detrimental to our health and potentially the health of the unborn. An interdisciplinary team of researchers from the University of Zurich noted that long-term stress during pregnancy could lead to a rise in the concentration of stress hormones in the amniotic fluid, whereas, short-term stress situations, do not seem to have a negative effect on the development of the fetus[1].

During periods of increased stress, the body releases corticotropin-releasing hormone (CRH), which in turn stimulates the production of cortisol. During pregnancy, the placenta can release CRH, which enters the amniotic fluid and impacts fetal metabolism[2].

The fetus obtains its cortisol from its mother until the third trimester when it starts producing it on its own. As a protective mechanism against short periods of maternal stress, a placental enzyme inactivates 80-90% of maternal cortisol before it enters the fetus. However, excess maternal cortisol can disrupt the fetal hypothalamic-pituitary-adrenal axis, which has been associated with long-term cognitive and behavioral problems in later life[3].   Although much more research is needed to understand the complexities of CRH ’s role and its effect in the development of the fetus, psychologists recommend that pregnant women who are exposed to long periods of stress seek support from a therapist to develop coping strategies to manage their stress.

     [1] “Too much stress for the mother affects the baby through the amniotic fluid.”

Science Daily. University of Zurich.  2017. Accessed February 12, 2019.

     [2] Ibid.

     [3] “The Impact of Maternal Stress on the Fetal Brain-A Summary of Key mechanisms.” Psychscenehub.  Accessed February 12, 2019.