We all know how important it is for expectant mothers to take care of their health throughout their pregnancy. There are even diet and lifestyle guidelines that you should follow to guarantee your baby the nutrients he needs to grow healthily.
However, the psychological state during pregnancy is usually forgotten, despite the fact that there are more and more scientific studies that reveal its impact on the baby.
Pregnancy should be a calm and exciting time in which the mother emotionally prepares to receive her baby. But it’s not always like this. There are a thousand and one factors that cloud this period, from financial difficulties and relationship problems to normal worries about motherhood or the health of the baby. And this state of emotional tension of the mother can take its toll on her children.
Prenatal anxiety translates into hostile and impulsive behavior in children
Researchers at California State University analyzed data from 55 studies in which participated more than 45,000 people. In these investigations, was evaluated the psychological distress of women during pregnancy (including stress, depression and anxiety), as well as the “externalizing behaviors” of their children; That is, the external symptoms that reveal mental health problems, such as hyperactivity or aggression.
The scientists found that women who reported more anxiety, depression or stress during pregnancy were more likely to have children with ADHD or who showed more aggressive, hostile and impulsive behaviors, as reported by parents or teachers.
Previous psychological research had already suggested the existence of a link between the mental health of mothers during pregnancy and the externalizing behaviors of children. However, these studies had not differentiated between the effects of stress, anxiety or depression during pregnancy and the consequences of this psychological distress after the birth of children.
What is novel about the current study is that these researchers analyzed the level of psychological distress of mothers both during and after pregnancy, so they were able to verify that prenatal stress is a risk factor for children developing behavioral problems, regardless of their gender. And this tendency towards hyperactivity, hostility and impulsivity continued until adolescence, although it was more notable during early childhood, from 2 to 5 years old.
How does maternal stress affect babies during pregnancy?
More and more neuroscientists agree that exposure to stress hormones in utero can affect children’s brain development. A study previously carried out at the University of Wisconsin, for example, found that mothers’ stress can alter their children’s genetics, causing connections to form in their brains that will end up influencing their reaction to adversity.
To understand the magnitude of its impact, we must understand its mechanism of action.
Glucocorticoids, cortisol in humans, are hormones that play a fundamental role in normal development, being the end product of the hypothalamic-pituitary-adrenal (HPA) axis, one of our body’s main stress response systems.
Interestingly, maternal cortisol increases two to four times during a normal pregnancy. In fact, it is essential during the last trimester because it stimulates the maturation of the lungs and prepares the baby for birth. Glucocorticoids also play a vital role in normal infant brain development, especially influencing neural systems involved in emotion regulation, cognitive function, and behavioral control.
The baby’s level of exposure to cortisol is regulated by a placental enzyme called 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), which oxidizes it to its inactive form, cortisone. Placental 11β-HSD2 levels also increase as pregnancy progresses, providing some protection to the fetus from maternal cortisol during critical stages of its development.
However, placental 11β-HSD2 is only a partial barrier, not insurmountable, so active maternal cortisol can cross the placenta. For this reason, fetal cortisol levels increase or decrease depending on the level of stress during pregnancy.
When cortisol rises too high due to stress or anxiety, particularly during vulnerable periods of fetal development, it can have a neurotoxic action. In this sense, another research carried out at the University of British Columbia revealed that when mothers were depressed or anxious, the gene responsible for activating stress hormone receptors was often silenced in newborns. This made that they show more fearful, more difficult it was for them to adapt to changes and they would had more problems dealing with stressful situations.
Therefore, prenatal exposure to high levels of maternal cortisol can lead to increased irritability in children, problems regulating their emotions, and therefore more disruptive and hostile behaviors.
The good news is that stress is a controllable risk factor. If you are pregnant, you can use relaxation techniques, breathing exercises or mindfulness meditation to regain your mental balance. Massages, relaxing baths or walks in nature will also help release tension and reduce cortisol levels. Additionally, you can ask a psychologist for help if you notice excessive stress.
Tung, I. et. Al. (2023) Prenatal stress and externalizing behaviors in childhood and adolescence: A systematic review and meta-analysis. Psychological Bulletin; 10.1037.
Essex, M. J. et. Al. (2013) Epigenetic Vestiges of Early Developmental Adversity: Childhood Stress Exposure and DNA Methylation in Adolescence. Child Development; 84(1): 58-75.
Poggi, E. & Sandman, C. A. (2010) The Timing of Prenatal Exposure to Maternal Cortisol and Psychosocial Stress is Associated with Human Infant Cognitive Development. Child Dev; 81(1): 131–148.
Oberlander, T. F. et. Al. (2008) Prenatal exposure to maternal depression, neonatal methylation of human glucocorticoid receptor gene (NR3C1) and infant cortisol stress responses. Epigenetics; 3(2): 97-106.