Meta-analysis found gestational cannabis exposure associated with a 30% increased risk of autism spectrum disorder and a 13% increase in ADHD, while a large cohort study found cannabis use disorder before or during pregnancy linked to 3x higher ASD risk.
Pregnant individuals considering cannabis use, obstetricians, neurodevelopmental researchers
RR 1.30 for ASD (meta-analysis)
What the researchers found
Meta-analysis of 13 studies found gestational cannabis exposure associated with ASD (RR 1.30) and ADHD (RR 1.13, possibly supported by publication bias). A separate cohort study (n=222,534) found peri-pregnancy cannabis use disorder associated with ASD (RRs 3.02-3.21), with larger effects in nonsmokers (RRs 4.55-4.83) than smokers (RRs 1.74-1.87).
Why it matters
Up to 10% of women may use cannabis during pregnancy, and constituents cross the placental barrier to act on cannabinoid receptors in the developing fetal brain. Understanding neurodevelopmental risks is essential for informed decision-making.
The numbers in context
ASD meta-analysis RR: 1.30 (4 studies, N=178,565). ADHD meta-analysis RR: 1.13 (10 studies, N=203,783). Cohort study CUD and ASD: RR 3.02-3.21 (n=222,534). Nonsmokers: RR 4.55-4.83. Smokers: RR 1.74-1.87.
How the study worked
Review of a meta-analysis (4 ASD studies, pooled N=178,565; 10 ADHD studies, pooled N=203,783) plus a large retrospective cohort study (n=222,534) examining associations between prenatal cannabis exposure and neurodevelopmental outcomes.
What this study cannot tell us
The ADHD finding may be influenced by publication bias. Cannot separate cannabis effects from genetic, environmental, or behavioral confounders. Small total number of exposed pregnancies worldwide. CUD is a proxy for heavy use, not any use.
How to read the evidence
Meta-analysis of observational studies plus large cohort, but observational design cannot establish causation and confounding remains possible.
When this study was published
2024 review of a meta-analysis and large cohort study
The bigger picture
The field connecting prenatal cannabis to neurodevelopmental outcomes is still nascent, with relatively small numbers of cannabis-exposed pregnancies studied globally. The difference between the meta-analysis (RR 1.30) and cohort study (RR ~3.0) may reflect differences in exposure measurement, with CUD representing heavier use.
Questions still open
- Why was the ASD risk higher in nonsmokers than smokers? Is the association driven by heavy use (CUD) specifically, or does any prenatal exposure carry risk?
Common questions
Does prenatal cannabis cause autism?
Why was the risk higher for nonsmokers?
Read the original research
Maternal Cannabis Use in Pregnancy and Autism Spectrum Disorder or Attention-Deficit/Hyperactivity Disorder in Offspring.
The Journal of clinical psychiatry, 86(1)
Citation
Andrade, Chittaranjan. (2024). Maternal Cannabis Use in Pregnancy and Autism Spectrum Disorder or Attention-Deficit/Hyperactivity Disorder in Offspring.. The Journal of clinical psychiatry, 86(1). https://doi.org/10.4088/JCP.24f15717
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