Maternal Cannabis Use Before (Not During) Pregnancy Was Linked to Higher Autism Symptoms in Children
In a prospective study of 4,380 children, maternal cannabis use before pregnancy (but not during) was associated with higher autism symptoms across childhood, while continued maternal tobacco use during pregnancy was independently linked to autism symptoms at age 6.
Quick Facts
What This Study Found
Maternal cannabis use before but not during pregnancy was associated with higher CBCL autism symptoms across childhood (beta: 0.33, CI: 0.02-0.63). Paternal cannabis use was also linked to higher CBCL symptoms (beta: 0.27, CI: 0.05-0.50) but was explained by maternal psychopathology. Continued maternal tobacco use during pregnancy was associated with SRS autism symptoms at age 6 (beta: 0.03, CI: 0.003-0.05), but paternal tobacco was not, suggesting intrauterine rather than familial effects.
Key Numbers
4,380 children; maternal preconception cannabis: beta 0.33 (CI: 0.02-0.63) for CBCL autism; paternal cannabis: beta 0.27 (CI: 0.05-0.50) for CBCL; no association with SRS autism; maternal continued tobacco: beta 0.03 (CI: 0.003-0.05) for SRS autism; no paternal tobacco association
How They Did This
Prospective population-based cohort (n=4,380) measuring parental cannabis and tobacco use via questionnaires and maternal cannabis metabolites via urinalysis. Autism symptoms measured using CBCL at ages 1.5, 3, and 6, and SRS at age 6. Linear mixed models and linear regression used.
Why This Research Matters
This study separates the effects of preconception vs. prenatal cannabis exposure and maternal vs. paternal use, helping distinguish between direct in utero effects and familial/genetic confounding. The finding that preconception (not prenatal) cannabis use predicts autism symptoms suggests epigenetic or selection effects rather than direct fetal exposure.
The Bigger Picture
The pattern of results suggests that cannabis-related autism risk may operate through family-level factors (genetics, parental psychopathology) rather than direct in utero exposure, while tobacco appears to have a genuine intrauterine effect since only maternal (not paternal) use predicted symptoms.
What This Study Doesn't Tell Us
Self-reported substance use (though supplemented with urinalysis for cannabis), observational design cannot prove causation, autism symptoms measured by mother report not clinical diagnosis, effect sizes are small, cannot rule out all confounding
Questions This Raises
- ?Why would preconception cannabis use predict child autism symptoms if prenatal use does not?
- ?Could epigenetic changes from cannabis use persist beyond cessation?
- ?Does maternal psychopathology (which explains the paternal cannabis association) independently affect child neurodevelopment?
Trust & Context
- Key Stat:
- Preconception, not prenatal, cannabis use was associated with higher autism symptoms in children
- Evidence Grade:
- Large prospective cohort with biological verification of cannabis exposure and longitudinal symptom measurement; strong design but observational
- Study Age:
- Published 2025
- Original Title:
- The association of preconception and prenatal cannabis and tobacco exposure with autism symptoms in offspring: A population-based longitudinal study.
- Published In:
- Neurotoxicology and teratology, 112, 107561 (2025)
- Authors:
- Cajachagua-Torres, Kim N(4), Boer, Olga D, Louwerse, Anneke, Ghassabian, Akhgar, Reiss, Irwin K M, Jaddoe, Vincent W V, El Marroun, Hanan
- Database ID:
- RTHC-06145
Evidence Hierarchy
Enrolls participants and follows them forward in time.
What do these levels mean? →Frequently Asked Questions
Does cannabis use during pregnancy cause autism?
In this study of 4,380 children, cannabis use during pregnancy was not associated with autism symptoms. Surprisingly, cannabis use before pregnancy was linked to higher symptoms, suggesting the association may reflect family-level factors rather than direct fetal exposure.
Is tobacco use during pregnancy linked to autism?
Yes. Maternal continued tobacco use during pregnancy was associated with autism symptoms at age 6, and since paternal tobacco showed no association, the effect appears to be from direct in utero exposure rather than shared family factors.
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Cite This Study
https://rethinkthc.com/research/RTHC-06145APA
Cajachagua-Torres, Kim N; Boer, Olga D; Louwerse, Anneke; Ghassabian, Akhgar; Reiss, Irwin K M; Jaddoe, Vincent W V; El Marroun, Hanan. (2025). The association of preconception and prenatal cannabis and tobacco exposure with autism symptoms in offspring: A population-based longitudinal study.. Neurotoxicology and teratology, 112, 107561. https://doi.org/10.1016/j.ntt.2025.107561
MLA
Cajachagua-Torres, Kim N, et al. "The association of preconception and prenatal cannabis and tobacco exposure with autism symptoms in offspring: A population-based longitudinal study.." Neurotoxicology and teratology, 2025. https://doi.org/10.1016/j.ntt.2025.107561
RethinkTHC
RethinkTHC Research Database. "The association of preconception and prenatal cannabis and t..." RTHC-06145. Retrieved from https://rethinkthc.com/research/cajachagua-torres-2025-the-association-of-preconception
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.