In a study of 2,577 mother-child pairs, prenatal cannabis exposure (combined with tobacco) was associated with higher cortisol levels in children at age 6, suggesting lasting effects on stress hormone regulation.
Pregnant women, obstetricians, pediatricians, researchers studying prenatal substance exposure effects
Higher cortisol levels at age 6 linked to prenatal cannabis exposure
What the researchers found
Children exposed to cannabis during pregnancy (combined with tobacco) had significantly higher hair cortisol concentrations at age 6 (log-10 difference 0.16, 95% CI 0.04-0.28). This was not mediated by birth weight. Paternal cannabis use and maternal tobacco-only use were not associated with childhood cortisol changes.
Why it matters
Elevated cortisol in childhood is linked to increased stress reactivity and vulnerability to mental health conditions. If prenatal cannabis exposure permanently alters the stress hormone system, this could have lifelong health implications.
The numbers in context
2,577 mother-child pairs; hair cortisol measured at age 6; significant cortisol increase with cannabis+tobacco exposure; no effect from tobacco alone or paternal use; not mediated by birth weight
How the study worked
Population-based prospective birth cohort of 2,577 mothers and children. Parental substance use collected by questionnaire with urine confirmation. Child hair cortisol and cortisone measured at age 6 as biomarkers of long-term HPA-axis functioning.
What this study cannot tell us
Cannabis exposure was combined with tobacco in most cases, making it difficult to isolate cannabis-specific effects. Self-reported substance use may underestimate true exposure. Hair cortisol reflects average levels and may miss acute fluctuations.
How to read the evidence
Large prospective birth cohort with objective biomarker measurement, though cannabis and tobacco exposure were difficult to separate
When this study was published
Published in 2021. Long-term follow-up of these children could reveal whether cortisol changes persist and affect health outcomes.
The bigger picture
This adds a specific biological mechanism to concerns about prenatal cannabis exposure, showing that the developing stress response system may be permanently altered, potentially increasing vulnerability to anxiety, depression, and stress-related conditions later in life.
Questions still open
- Can the cortisol elevation be attributed to cannabis alone or is the tobacco combination necessary? Do these cortisol changes persist into adolescence and adulthood? What are the behavioral and mental health consequences of this altered HPA-axis functioning?
Common questions
Does cannabis use during pregnancy affect children long-term?
What does elevated cortisol in children mean?
Read the original research
Parental cannabis and tobacco use during pregnancy and childhood hair cortisol concentrations.
Drug and alcohol dependence, 225, 108751
Citation
Cajachagua-Torres, Kim N; Jaddoe, Vincent W V; de Rijke, Yolanda B; van den Akker, Erica L T; Reiss, Irwin K M; van Rossum, Elisabeth F C; El Marroun, Hanan. (2021). Parental cannabis and tobacco use during pregnancy and childhood hair cortisol concentrations.. Drug and alcohol dependence, 225, 108751. https://doi.org/10.1016/j.drugalcdep.2021.108751
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