A review found that cannabis use during pregnancy is associated with reduced pro-inflammatory cytokines in the placenta, which was linked to increased anxiety, aggression, and hyperactivity in offspring, though the field is still too young for firm conclusions.
Pregnant individuals considering cannabis use, perinatal researchers, developmental neuroscientists
Reduced placental cytokines from prenatal cannabis linked to offspring anxiety, aggression, and hyperactivity
What the researchers found
In both human and rodent studies using vaporized exposure, cannabis use during pregnancy was associated with reduced pro-inflammatory cytokine levels in the placenta. In humans, this reduction was linked to increased offspring anxiety, aggression, and hyperactivity. Prenatal cannabis exposure also appeared to impact T cell dynamics in various organs.
Why it matters
Cannabis use among pregnant people is increasing alongside legalization and growing social acceptability. Understanding how prenatal exposure might affect offspring through immune pathways could reveal new mechanisms of risk and potentially inform harm reduction strategies.
The numbers in context
The review notes increasing legalization and permissiveness globally; cannabinoid receptors are abundantly expressed in the immune system; specific cytokine reductions were observed in placental tissue; offspring showed increased anxiety, aggression, and hyperactivity behaviors
How the study worked
Narrative review synthesizing research on prenatal cannabis exposure (PCE) across human and animal studies, focusing specifically on immune system changes (both central nervous system and peripheral) as potential mediators of offspring mental health effects.
What this study cannot tell us
The field is described as "too nascent for robust conclusions." Limited data on central nervous system immune cells (microglia). The link between immune cell changes and mental health outcomes needs further establishment. Animal models may not fully replicate human exposure patterns.
How to read the evidence
Preliminary: narrative review of an emerging field with limited studies, especially regarding immune-mediated pathways. Authors themselves note the field is too nascent for robust conclusions.
When this study was published
2026 review synthesizing recent research on prenatal cannabis and immune effects.
The bigger picture
This connects two growing fields: prenatal cannabis effects and neuroimmunology. The immune system is increasingly recognized as a mediator of mental health, and the placenta is a key interface where cannabis exposure could have lasting effects on fetal development.
Questions still open
- Do different cannabinoids (THC vs. CBD) have distinct immune effects on the placenta? At what gestational stage is the fetus most vulnerable to immune disruption from cannabis? Could monitoring placental cytokines predict offspring mental health risk?
Common questions
How might cannabis during pregnancy affect the baby through the immune system?
Is this conclusion definitive?
Read the original research
Effects of prenatal cannabis exposure on offspring mental health: A focus on the role of the immune system.
Neuroscience and biobehavioral reviews, 181, 106488
Citation
Vecchiarelli, Haley A; Baglot, Samantha L; Black, Tallan; Choi, Esther Y; Cupo, Lani; Sandberg, Colby; Siron, Léa; Chakravarty, M Mallar; Hill, Matthew N; Howland, John G; Khokhar, Jibran Y; Tremblay, Marie-Ève. (2026). Effects of prenatal cannabis exposure on offspring mental health: A focus on the role of the immune system.. Neuroscience and biobehavioral reviews, 181, 106488. https://doi.org/10.1016/j.neubiorev.2025.106488
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