Repeated stressful events experienced by women during pregnancy can increase the risk of behavioural problems in their children, according to a new study.
Common stressful events such as financial and relationship problems, difficult pregnancy, job loss, and major life stressors like a death in the family have a direct correlation with behavioural problems in children, the study finds.
Released by the Telethon Institute for Child Health Research in Perth, Australia, the study was published online in the latest edition of the international journal Development and Psychopathology.
Registered psychologist Dr. Monique Robinson, lead author of the study, said that although previous studies have shown a link between stress and negative effects, this one goes further by analysing the timing, amount, and kinds of events that lead to poorer outcomes.
“What we have found is that it is the overall number of stresses that is most related to child behaviour outcomes,” she said. “Two or fewer stresses during pregnancy are not associated with poor child behavioural development, but as the number increases to three or more, then the risks of more difficult child behaviour increases.”
The actual type of stress experienced was of less importance than the number of stresses, Robinson said, and there was no specific risk associated with the timing of the stressful events—whether they occurred early or late in the pregnancy.
The research was based on data from the long-term Raine Study, which began in 1989 and recruited 2,900 pregnant women at a Perth hospital. A wide variety of information was collected on both parents and on the child, both prenatally and after birth.
The mother’s experience of life stress events and child behavioural assessments were also recorded when the children were followed up at ages 2, 5, 8, 10, and 14 years using a questionnaire called the Child Behaviour Checklist.
The percentage of women with more than two stress events was 37.2 percent, while the percentage with six or more was 7.6 percent.
However, Robinson noted that the study should not make pregnant women feel anxious about the stress in their lives.
“These types of analyses look at overall population risk, and of course individuals can have very differing responses,” she said.
“Regardless of exposure to stress in the womb, a nurturing environment after birth can provide the child with enormous potential to change their course of development. This is known as ‘developmental plasticity,’ which means that the brain can adapt and change as the child grows with a positive environment.
What’s important, she added, is providing support for pregnant women, particularly those in low brackets.
“If we think about people who lead stressful lives, they are most often linked with socioeconomic disadvantage. This research shows we should be targeting these women with support programs to ensure the stress does not negatively affect the unborn child.”
A recent study in Denmark found that prenatal stress was a major factor in miscarriages. The researchers attributed this to stress hormones that tended to restrict the much-needed blood flow to the placenta and the foetus. A 2009 study in the American Journal of Public health showed a strong correlation between stress in the mother and low birth weight.
As for the Perth study, Dr. Robinson said further research is needed to understand the mechanisms behind how stress in pregnancy affects the developing baby, including the impact of maternal stress hormones, attachment and parenting issues, and socioeconomic factors.