A systematic review found prenatal cannabinoid exposure significantly disrupts the monoamine neurotransmitter system in animal studies, with limited human evidence suggesting cognitive and behavioral risks.
Prenatal researchers, neuroscientists studying fetal development, clinicians counseling pregnant patients about cannabis.
170% increase in prenatal cannabis use (2009-2016)
What the researchers found
After screening 18,252 papers, only 16 animal and 4 human studies met criteria. Animal models revealed significant disruptions in neurotransmitter regulation, receptor function, and gene expression following prenatal cannabis exposure. Human studies suggested potential cognitive and behavioral risks for offspring. No studies directly addressed the monoamine system in the placenta, exposing a critical research gap.
Why it matters
Cannabis use during pregnancy increased 170% between 2009 and 2016. The monoamine system (dopamine, serotonin, norepinephrine) is crucial for both placental function and fetal brain development. This review reveals that while animal evidence of disruption is strong, we lack the human studies needed to fully understand the risks.
The numbers in context
18,252 papers initially screened. 20 studies met inclusion criteria (16 animal, 4 human). Cannabis use during pregnancy increased 170% between 2009-2016.
How the study worked
Systematic review following PRISM guidelines with comprehensive database search. From 18,252 initial papers, rigorous screening yielded 16 animal studies and 4 human studies. Findings were synthesized to evaluate effects on neurotransmitter regulation, receptor function, and gene expression within the fetoplacental unit, framed through the Developmental Origins of Health and Disease (DOHaD) framework.
What this study cannot tell us
Only 4 human studies met criteria, severely limiting clinical conclusions. Animal models use controlled cannabinoid exposure that may not reflect human use patterns. No studies examined monoamine effects specifically in placental tissue. Review cannot determine thresholds for harmful exposure.
How to read the evidence
Moderate: systematic review with rigorous methodology, but limited by the small number of qualifying studies (especially human studies).
When this study was published
2025 study
The bigger picture
The dramatic gap between animal evidence (showing clear neurotransmitter disruption) and human evidence (only 4 studies) highlights how little we know about prenatal cannabis effects on fundamental brain chemistry. As cannabis use during pregnancy rises, this knowledge gap becomes increasingly urgent.
Questions still open
- At what exposure level does prenatal cannabis begin to disrupt the monoamine system? Are the animal findings on neurotransmitter disruption translatable to human pregnancy? Does the monoamine disruption explain some of the cognitive and behavioral outcomes seen in exposed children?
Common questions
Does cannabis during pregnancy affect the baby's brain chemistry?
Why is there so little human research on this?
Read the original research
Effects of prenatal cannabinoid use on the monoamine system in the fetoplacental unit: A systematic review of animal and human studies.
Drug and alcohol dependence, 268, 112579
Citation
Portillo, Ramon; Synova, Tetiana; Staud, Frantisek. (2025). Effects of prenatal cannabinoid use on the monoamine system in the fetoplacental unit: A systematic review of animal and human studies.. Drug and alcohol dependence, 268, 112579. https://doi.org/10.1016/j.drugalcdep.2025.112579
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