Large study found no link between prenatal cannabis use and child autism
In nearly 179,000 pregnancies, maternal cannabis use in early pregnancy was not associated with child autism spectrum disorder after adjusting for maternal characteristics, contradicting some earlier studies.
Quick Facts
What This Study Found
After adjustment for maternal characteristics, prenatal cannabis use was not associated with child ASD (HR 1.05, 95% CI 0.84-1.32). No dose-response relationship was observed. No sex-specific associations were found (males: HR 1.01; females: HR 1.19).
Key Numbers
178,948 pregnancies. 8,486 (4.7%) screened positive for cannabis. ASD diagnosed in 3.6% of children. Adjusted HR: 1.05 (95% CI 0.84-1.32). Males HR: 1.01. Females HR: 1.19.
How They Did This
Population-based retrospective birth cohort of 178,948 singleton pregnancies among 146,296 Kaiser Permanente Northern California members (2011-2019). Cannabis use screened via self-report and urine toxicology at ~8-10 weeks gestation. ASD identified by ICD-10 codes from EHR.
Why This Research Matters
A previous meta-analysis found a 30% increased ASD risk with prenatal cannabis exposure, but this larger, well-controlled study found no association after adjusting for confounders, suggesting earlier findings may have been driven by unmeasured variables.
The Bigger Picture
The contrast between this null finding and earlier positive associations underscores how important confounding adjustment is in observational cannabis research. Maternal characteristics that predict both cannabis use and ASD risk (mental health, other substance use) may drive apparent associations.
What This Study Doesn't Tell Us
Cannabis use assessed only at early prenatal care entry. Cannot rule out effects of use later in pregnancy. EHR-based ASD diagnosis may differ from research-standard assessment. Children born 2019 had limited follow-up time for ASD diagnosis.
Questions This Raises
- ?Why do some studies find a cannabis-ASD link while this one does not?
- ?Is the difference primarily about confounding adjustment?
- ?Would studies of heavier or later-pregnancy use find different results?
Trust & Context
- Key Stat:
- Adjusted HR 1.05 (not significant)
- Evidence Grade:
- Large population-based cohort with objective screening and confounder adjustment provides strong evidence, though limited to early-pregnancy exposure.
- Study Age:
- 2024 study of Kaiser Permanente data from 2011-2019
- Original Title:
- Maternal Prenatal Cannabis Use and Child Autism Spectrum Disorder.
- Published In:
- JAMA network open, 7(10), e2440301 (2024)
- Authors:
- Avalos, Lyndsay A(13), Shenkute, Mahlet, Alexeeff, Stacey E(19), Oberman, Nina, Croen, Lisa A, Davignon, Meghan, Adams, Sara R, Ansley, Deborah, Castellanos, Carley, Young-Wolff, Kelly C
- Database ID:
- RTHC-05099
Evidence Hierarchy
Frequently Asked Questions
Does this contradict studies linking cannabis to autism?
Partially. Earlier studies, including a meta-analysis, found associations, but this larger study with better confounding adjustment found none. The difference may be that earlier studies did not fully account for maternal characteristics that predict both cannabis use and ASD risk.
Should pregnant people stop worrying about cannabis and autism?
The study found no ASD link specifically, but prenatal cannabis is still associated with other adverse outcomes. The authors recommend clinicians continue advising against use during pregnancy.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-05099APA
Avalos, Lyndsay A; Shenkute, Mahlet; Alexeeff, Stacey E; Oberman, Nina; Croen, Lisa A; Davignon, Meghan; Adams, Sara R; Ansley, Deborah; Castellanos, Carley; Young-Wolff, Kelly C. (2024). Maternal Prenatal Cannabis Use and Child Autism Spectrum Disorder.. JAMA network open, 7(10), e2440301. https://doi.org/10.1001/jamanetworkopen.2024.40301
MLA
Avalos, Lyndsay A, et al. "Maternal Prenatal Cannabis Use and Child Autism Spectrum Disorder.." JAMA network open, 2024. https://doi.org/10.1001/jamanetworkopen.2024.40301
RethinkTHC
RethinkTHC Research Database. "Maternal Prenatal Cannabis Use and Child Autism Spectrum Dis..." RTHC-05099. Retrieved from https://rethinkthc.com/research/avalos-2024-maternal-prenatal-cannabis-use
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.