An article in the April issue of Acta Psychiatrica Scandinavica reports the results of a longitudinal study which found that individuals whose mothers experienced subjective stress during pregnancy have increased odds of being diagnosed with a psychiatric disorder (especially mood disorders). This effect was independent of mothers’ depressive symptoms, psychiatric history, or smoking while pregnant.1
Studying Stress During Pregnancy
Data came from the Helsinki Longitudinal Temperament Cohort, a study of a birth cohort of nearly 6,500 people (born in 1975/1976 in Finland) who had been followed until the age of 30. For this investigation, researchers could use data only from individuals whose mothers had completed one or more health questionnaire during their pregnancy. As a result, the final sample comprised 3,626 individuals.
The health questionnaires consisted of 15 questions; these addressed various physical and mental health issues the mothers may have experienced the previous month (e.g., sleep difficulties, mood changes). The primary outcomes of interest were psychiatric diagnoses (psychosis, mood and anxiety disorders) in their children (up to the age of 30), as determined based on the Finnish Hospital Discharge Register records.
Also measured were a variety of potential confounds, like the number of questionnaires returned by the mothers, both mothers’ and fathers’ psychiatric history, prenatal smoking, and maternal feelings of depression at the time of pregnancy.
Mothers’ Pregnancy Stress and Mental Illness in Their Children
Descriptive statistics showed that the mothers were, on average, 27 years old when they gave birth. About 82 percent reported experiencing at least one instance of emotional stress while pregnant; only 6 percent were diagnosed with one or more mental disorders (most commonly, anxiety disorders).
Logistic regression models were used to analyze the data, and the results suggested that individuals born to mothers who reported feeling stressed during pregnancy had greater odds (OR = 1.41, 95 percent CI = 1.10–1.81) of developing a mental illness. And there was a 1.7-fold increased odds of a mood disorder diagnosis in those born to mothers who experienced stress while pregnant (OR = 1.67, 95 percent CI = 1.10–2.54).
The current research found that mothers who reported subjective stress at the time of pregnancy were more likely to have children who would eventually be diagnosed with a mental illness—in particular, a mood disorder like depression. This effect was independent of parental psychiatric history, mothers’ smoking during pregnancy, and mothers’ depressive symptoms. The question is why. At this point, the answer is not clear. Some possibilities include:
- Stress may have an immediate biological effect on brain development in the fetus—for instance, by altering the regulation of the hypothalamic–pituitary–adrenal axis.2
- Stress might have an indirect effect; for example, mothers who are more stressed might exercise less often or have higher blood pressure, and these would negatively affect their babies’ health.1
- Another possibility is an epigenetic process such as methylation of a receptor gene in children born to stressed mothers.3
- A fourth explanation involves the child’s rearing environment. Mothers who experience stress during pregnancy may be more likely to feel stressed afterward too, and as a result, be less able to provide high-quality parenting or establish secure attachment relationships with their children. These factors—poor parenting, family conflict and dysfunction, and insecure attachment—can increase susceptibility to psychiatric illness in their children.1
Regardless of which of the above (or other) explanations will receive more empirical support in future research, the results of this investigation show that “it is possible to identify women whose offspring may be at risk of developing a psychiatric disorder through simply asking about stress and well-being during pregnancy.” Having identified these women, it is important to assist them in getting the help they need: “Women, who are experiencing significant stress during pregnancy, in the absence of psychiatric disorder, may benefit from psychosocial counseling or other supportive intervention” (p. 308).1
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1. Brannigan, R., Cannon, M., Tanskanen, A., Huttunen, M. O., Leacy, F. P., & Clarke, M. C. (2019). The association between subjective maternal stress during pregnancy and oﬀspring clinically diagnosed psychiatric disorders. Acta Psychiatrica Scandinavica, 139(4), 304–310.
2. Entringer, S., Kumsta, R., Hellhammer, D. H., Wadhwa, P. D., & Wust, S. (2009). Prenatal exposure to maternal psychosocial stress and HPA axis regulation in young adults. Hormones and Behavior, 55, 292–298.
3. Oberlander, T.F., Weinberg, J., Papsdorf, M., Grunau, R., Misri, S., & Devlin, A.M. (2008). Prenatal exposure to maternal depression, neonatal methylation of human glucocorticoid receptor gene (NR3C1) and infant cortisol stress responses. Epigenetics, 3, 97–106.