A mom’s lifetime stress may affect their child’s brain function, Stanford researchers find

Researchers at the March of Dimes Prematurity Research Center (PRC) at Stanford Medicine have found a link between the adverse events a woman experiences before pregnancy and the way their child’s brain functions around three to five years old. 

Specifically, the researchers found that moms who experienced stress as children, teens, and young women had children who needed to use more “brain power,” or neurological resources like oxygen, to inhibit an impulsive behavior than did the children of women with a less stressful life history. 

In addition, the study found that children who are “less temperamentally regulated,” or more prone to experiencing negative emotions and difficulties with self-control, needed to use extra brain power to inhibit their impulsive behavior, too. This means that a child’s personality, not just a mom’s stress, affects that child’s brain function. Still, study authors pointed out the link between maternal stress and a child’s brain function was stronger than the link between that child’s personality and brain function. 

The study, published October 2022 in the scientific journal Developmental Psychobiology, was led by Dr. Jonas Miller, a former Stanford postdoctoral researcher and current University of Connecticut Psychological Sciences Assistant Professor. 

It involved 36 mother-child pairs who underwent two types of testing for the study. First, the moms were asked to answer questions about adverse experiences in their lives (miscarriage, being involved in an accident, experiencing the death of a loved one, and more) adverse experiences in their child’s life (separation anxiety, illness, bullying, spanking, and more) and their child’s temperament- the child’s experiences relative to fear, laugher, shyness, smiling, inhibitory control, soothability, and more. 

Second, the children were asked to play a go/no go video game while wearing an fNIRS cap- a device that, when placed on the scalp, measures the blood oxygen in an activated part of the brain.

When a part of the brain is working harder to do a task, more oxygenated blood is sent to that region to fuel the brain activity. Dr. Miller and his team wanted to see if there were atypical patterns of brain oxygenation among children with more difficult temperaments and those whose moms experienced adverse events. 

In the experiment, the children were told to touch a computer screen each time they saw a cartoon picture of a sun and not to touch each time they saw clouds. This go/no go or touch/don’t touch experiment was an exercise in inhibitory control, a skill that is considered important for children to succeed in the world. Could the children follow instructions and not touch the screen when they likely wanted to touch it, Dr. Miller wondered? And was this type of control easy for them? Most importantly, were there differences in the “brain power,” or oxygenated blood needed to accomplish the task, between different children? 

The study found that both children whose moms did experience stress and those whose didn’t experience a lot of stress showed similar inhibitory control in terms of their behavioral performance on the task (avoided touching the cloud). However, those whose moms experienced adverse events used more oxygenated blood in their prefrontal cortex during these moments of control than those whose didn’t.

“We saw that maternal adversity was not related to whether children performed well on the test,” Dr. Miller said. “But the brains of the ones whose mothers had adverse experiences had to work harder to do the same task- they literally needed more resources to fuel the activity in their prefrontal cortex.”

While Dr. Miller said that it would be incorrect to draw conclusions about a causal relationship between maternal stress and brain function in children, and that more, larger, and representative studies were needed on the topic, he said it was clear that maternal stress plays a role in what happens inside the brains of offspring. 

“A growing body of research has shown that stress has intergenerational consequences,” Dr. Miller said. “For example, stress during pregnancy is associated with biological processes like inflammation that serve as signals to the developing fetus about how the brain should be developing.”

“That in turn could put children at risk for the kinds of things we observed in this study- requiring more brain resources to accomplish a particular behavioral result.”

Interestingly, the study did not find a link between a mom’s stress during pregnancy, or a child’s stress in life, with higher oxygen levels in children’s brains during the test, likely just because, statistically, there were too few experiences to draw from in these short-interval life events. 

Dr. Miller said more research was necessary to investigate the exact pathways responsible for the link between maternal stress and brain development and function; to uncover whether these adverse maternal experiences have a fading or enduring effect on children; and to pinpoint exactly how much stress and what types of stress are negative for mom and child.

Dr. Miller agreed that eliminating stress (an unavoidable part of life) is not an option, and said he’s advocating for more trauma-informed care for children, increasing resources for moms and childcare providers and growing sources of resilience (like strong family and community bonds) for all children. 

“We need to redesign society in a way to better manage these kinds of really common events, we need to increase our support for moms and childcare providers, and we need to give kids tools to develop and maintain healthy relationships that they can fall back on and act as a buffer when things get rough.” 

Stanford is one of five March of Dimes Prematurity Research Centers conducting translational research into the causes of preterm birth. 

The centers - at Stanford (2011), the University of California San Francisco (2022), Imperial College London (2018), the University of Pennsylvania (2014) and the Ohio Collaborative (2013) - are working independently and together to conduct groundbreaking research that will lead to the development of diagnostic and therapeutic tools to predict and prevent preterm birth. 

The heart of our research program, our Prematurity Research Centers conduct inquiries that span the field of prematurity and maternal-fetal health, including research on the molecular and genetic mechanisms leading to preterm birth, the maternal microbiome and immune responses, maternal-placental contributions to preterm birth, environmental factors and social determinants, diagnostic biomarkers of preterm birth and maternal co-morbidities.

As the largest - and most interdisciplinary - scientific undertaking related to solving preterm birth, March of Dimes Prematurity Research Centers are at the forefront of breakthroughs that will fundamentally change pregnancy and birth in our lifetime.