Inheriting Stress Disorder-Linked Behavioural Malfunctions

"The roots of mental illness can be traced back to the very beginnings of life. We can't avoid all stress during pregnancy, or at any time. But we can help women avoid stress and manage stress."
"Research shows that when stressful things happen, people are likely to have mental health problems decades later."
"Having a supportive partner and family members helps. It's in everyone's best interests to help pregnant women reduce stress."
Dr. Ian Colman, associate professor, school of epidemiology and public health, University of Ottawa

"This study is certainly reflective about what we know about stress. It validates what we have been saying in the mental health community -- stress can be toxic."
"Resilience isn't about avoiding stress. It's about springing back and helping people do that."
"We can beat illnesses upstream. This impacts more than the mother."
Mark Henick, national director of strategic initiatives, Canadian Mental Health Association

Stressful times for mother increase the risk of later problems for her baby. Flickr/Roberto Carlos Pecino

In 2015 a study appeared in the journal Advanced Neurobiology suggesting that prenatal anxiety or depression may be responsible for between ten to fifteen percent of the attributable load for emotional or behavioural outcomes in children even while the biological mechanisms involved in the interaction are not yet known. The hormone cortisol which the pregnant woman expresses responding to stress is known to pass to the fetus through the placental barrier.

That fetal response theoretically links to behavioural problems in the emerging child. Testosterone is linked to fetal cortisol, and testosterone is linked to aggressive behaviour. Roughly ten percent of school-age children are diagnosed with what is termed conduct disorder, or ADHD. Other research published in 2014 in the Canadian Medical Association Journal concluded little evidence exists that greater numbers of children are emerging with behavioural disorders.

They are surfacing in greater numbers simply because the social stigma surrounding these fairly common behavioural disorders has dissipated leading parents to aggressively seek medical treatment for children exhibiting those symptoms. And therein lies another potential problem, when children acting out in what may be a normal manner which parents find difficult to handle are being diagnosed incorrectly and prescribed medications they don't actually need.


More recently a University of Ottawa study studying data on over 10,000 mother-child pairs has validated the theory that pregnant women experiencing significant stress increase the risk of producing a child with behavioural problems. Exposed to high levels of stress, expectant mothers had children twice as likely to exhibit chronic symptoms of hyperactivity as well as conduct disorders, according to the study published in the journal Biological Psychiatry.

Long-lasting or permanent alterations to the brain of a fetus can be caused through a mother's stress levels. The British Avon Longitudinal Study of Parents and Children which began in 1990 provided the data base for this study where mothers were prompted to describe stressful life events during pregnancy, citing problems in the workplace, illness or death of family members, or disagreements with a partner, family or friend.

Symptoms of conduct disorder in the children of the women interviewed were measured at ages six, nine and thirteen. Aggressive or anti-social behaviour associated with poor school performance, substance abuse, difficulties in personal relationships and criminal activity were all noted as reflective of conduct disorders. Building on those criteria, the University of Ottawa study included additional variables such as parental education, class, low-birth weight or premature birth, maternal smoking, drinking or mental health throughout pregnancy.

The study's lead author, Dr. Colman, added that mothers depressed or experiencing anxiety during pregnancy may continue feeling depressed or anxious during the child's formative growing years, which would also be likely to affect the child's behaviour. Additional research undertaken by this team led by Dr. Colman anticipates an increasingly complex study of the nature of specific stressors and how they would further impact children, in an effort to understand what types of prenatal stress may be specifically harmful.