Protecting babies from harmful stress

What does severe stress do to my baby?

Severe stress can cause lifelong health problems. This may be as a result of changes in the baby’s genes. Harmful stress can be caused by physical challenges such as poor health, being malnourished, pain, and extended periods of disturbed sleep. It can be caused by social problems such as extreme poverty, the absence of a supportive caregiver, neglect, and abuse. When genes are affected by harmful stress, they change the way the brain, hormonal, and other systems work, and the result can be chronic inflammation and other conditions that lead to various diseases. Mothers and other supportive caregivers are key to protecting babies from harmful stress, and breastfeeding has been shown to further reduce it.

A) Describing harmful stress

Many adult diseases are developmental disorders that start early in life. Before and shortly after birth, babies’ genes are permanently programmed to work in certain ways.  

Harmful (or toxic) stress can cause temporary or permanent changes in babies’ genes (Lapp 2019; Lester 2018). Genes control cell function and overall growth and development. When genes change, they change the way the brain, hormonal system, gut bacteria, and immune system work and interact (de Weerth 2013; Johnson 2013). If these systems are not working well, the result can be chronic inflammation and other conditions leading to disease including (McDade 2021; Shonkoff 2012):

  • Strokes and heart attacks (cardiovascular disease) 
  • Diabetes
  • Obesity
  • High blood pressure
  • Cancers
  • Asthma
  • Depression 

These genetic changes can be transmitted along to future generations.

B) Causes of harmful stress

The baby’s genes can be affected by harmful stress that is caused by:

For example, research has shown that four- and five-year-old children have gene differences related to how much human contact they had soon after birth (Moore 2017).

Another form of harmful stress results in extreme, frequent, or long-term activation of a baby’s stress response in the absence of a supportive caregiver. This can occur when parents and caregivers have social and mental health challenges resulting in neglect or abuse, extreme poverty, and family violence.

C) The effects of harmful stress on the brain

The human brain grows quickly during the first year of life, tripling in weight (Dekaban 1978). By comparison, a baby’s height increases only by about half during that time. The rapid growth of the brain makes it extremely vulnerable to harmful influences that can have lifelong effects.

There is clear evidence that excess stress can damage a baby’s brain, leading to future problems (Oyetunji 2020). Lack of secure attachment to one’s caregivers (bonding) has been shown to decrease the size of some parts of the brain that control social, thinking (cognitive), and emotional functioning (Kraaijenvanger 2020; Leblanc 2017).

Harmful stress decreases a baby’s ability to learn (Thompson 2007). Chronic stress has been shown to decrease the size of the hippocampus, the part of the brain involved in learning and memory (Salpolsky 1996).

The changes in the brain may also result in neurobehavioral problems during early childhood including attention deficit hyperactivity disorder and autism spectrum disorder (Casavant 2019).

Studies on rats have shown there is a critical time for turning on a gene that controls anxiety. One study (Champagne 2001) found that if the rat pups were not nurtured in the first 10 days of life, the gene was not turned on and the pups struggled with anxiety for the rest of their lives .

Harmful stress can result in the growth of the amygdala, a part of the brain that processes fear. It will send signals to other parts of the brain to trigger a flight-or-fight response. The over-responsive amygdala can create a chronically-activated stress response and feelings of fear and anxiety (McEwan 2017).   

As a child grows, all of these changes can result in illness and impaired social interactions, academic success, economic well-being, and further stress.

D) Breastfeeding can lower stress

1) Increasing maternal responsiveness and baby attachment

Breastfeeding acts in many ways to lower the baby’s stress and the effect can even be seen at the genetic level (Hallowell 2017; Lester 2018). 

Breastfeeding supports mother-baby bonding by bringing them together at regular intervals, allowing the baby to learn to recognize its mother and then relax in a familiar environment.

Mothers are key to protecting their babies from harmful stress by recognizing and responding to the baby’s needs (maternal responsiveness). Breastfeeding increases maternal responsiveness as mothers need to understand their babies’ hunger signs and other behaviours in order to breastfeed effectively

Breastfeeding encourages affectionate behaviour by mothers which protects babies against harmful stress, even when the mother is depressed (Hardin 2021).

2) Other ways that breastfeeding decreases the baby’s stress

Breastfeeding can further reduce stress by:

  • Reducing the risk of illness in the baby.
  • Helping babies get to sleep.
  • Keeping them warm.
  • Minimizing the pain of medical procedures.
  • Allowing the baby to control the amount of milk taken in and avoid overeating.


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