Clinical Takeaway
Children born to mothers who used cannabis during pregnancy showed a modest increase in risk for autism spectrum disorder and a smaller increase in risk for ADHD, based on pooled data from 13 observational studies. Cannabis compounds cross the placenta and may interfere with cannabinoid receptors involved in fetal brain development. These findings support current recommendations to avoid cannabis use during pregnancy.
#17 Maternal Cannabis Use in Pregnancy and Autism Spectrum Disorder or Attention-Deficit/Hyperactivity Disorder in Offspring.
Citation: Andrade Chittaranjan. Maternal Cannabis Use in Pregnancy and Autism Spectrum Disorder or Attention-Deficit/Hyperactivity Disorder in Offspring.. The Journal of clinical psychiatry. 2024. PMID: 39724097.
Design: 6 Journal: 0 N: 2 Recency: 1 Pop: 3 Human: 1 Risk: -2
- Preclinical only
Methodological Considerations:
- Retrospective design — selection and information bias risk
Abstract: Up to 10% of women may use cannabis during pregnancy; this is of concern because constituents of cannabis cross the placental barrier and potentially influence neurodevelopment by acting on cannabinoid receptors in the developing fetal brain. In this context, a recent meta analysis of 13 observational studies found that gestational exposure to cannabis was associated with a small increase in the risk of autism spectrum disorder (ASD; relative risk [RR], 1.30) and with an even smaller increase in the risk of attention deficit/hyperactivity disorder (ADHD; RR, 1.13); the latter finding was probably supported by publication bias. In this meta-analysis, 4 studies provided information on ASD (pooled N = 178,565) and 10 on ADHD (pooled N = 203,783). In a large (n = 222,534) retrospectively ascertained cohort study published after the meta-analysis, cannabis use disorder (CUD) recorded before pregnancy, during pregnancy, and during pregnancy plus the year after delivery were associated with closely similar increased risks of ASD (RRs, 3.02-3.21). The risks were smaller in smokers (RRs, 1.74-1.87) than in nonsmokers (RRs, 4.55-4.83) but differed little between male (RRs, 3.01-3.06) and female (RRs, 2.71-2.85) offspring. Although the cohort study had many strengths, its limitations permitted only the conclusion that peri-pregnancy exposure to CUD is associated with a large increase in the risk of ASD in offspring; it remained possible that much of the risk was driven by genetic, environmental, or behavioral variables. The field is nascent; the total number of cannabis exposed pregnancies (with ASD and ADHD as the outcomes) in world literature is small. However, cannabis use during pregnancy is, at the very least, a clear marker for adverse neurodevelopmental outcomes, besides the adverse maternal, fetal, and neonatal outcomes identified in other studies. Healthcare providers who manage women who use cannabis during pregnancy need to be aware of these adverse outcomes.
What This Study Teaches Us
Prenatal cannabis exposure, particularly when cannabis use disorder is present, is associated with a 3-fold increased risk of autism spectrum disorder in offspring. The risk appears smaller in mothers who smoke cannabis compared to those who don’t smoke, suggesting route of exposure may matter.
Why This Matters Clinically
Clinicians counseling pregnant women or women planning pregnancy need clear data on cannabis teratogenicity. This study elevates cannabis from an unknown risk to a documented concern for neurodevelopmental outcomes, making it relevant to preconception and prenatal counseling conversations.
Study Snapshot
| Study Design | Meta-analysis of 13 observational studies, plus discussion of a large retrospective cohort study (N=222,534) published after the meta-analysis |
| Population | Meta-analysis: 178,565 for ASD outcomes, 203,783 for ADHD outcomes. Cohort study: 222,534 pregnancies with documented cannabis use disorder status |
| Intervention | Maternal cannabis use during pregnancy, assessed as general use in meta-analysis and as cannabis use disorder diagnosis (CUD) in cohort study |
| Primary Outcome | Autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) diagnosis in offspring |
| Key Result | Meta-analysis: RR 1.30 for ASD, RR 1.13 for ADHD with gestational cannabis exposure. Cohort study: RR 3.02-3.21 for ASD with documented CUD; lower risk in smokers (RR 1.74-1.87) than nonsmokers (RR 4.55-4.83) |
Where This Paper Deserves Skepticism
The meta-analysis pooled observational studies with inherent confounding limitations; the ADHD finding appears vulnerable to publication bias. The large cohort study, while impressive in size, is retrospective and documented CUD diagnoses, not actual consumption patterns, which may introduce misclassification. Critically, the authors themselves acknowledge that unmeasured genetic, environmental, and behavioral variables could explain much of the observed association with CUD. The abstract breaks off mid-sentence, and the total number of exposed pregnancies in the global literature remains small.
Dr. Caplan’s Take
I read this as a serious signal that deserves preconception and prenatal attention, but not yet as definitive proof of causation. The dose-response gradient from meta-analysis (smaller RR 1.30) to the CUD cohort (larger RR 3.02-3.21) is biologically plausible, and the cannabis exposure route effect (smokers lower risk than nonsmokers) hints at real pharmacology rather than pure confounding. However, women with CUD often carry other risk factors for adverse outcomes, and we cannot yet untangle those from the cannabis itself. My clinical practice is to counsel women planning pregnancy or pregnant women that cannabis use is associated with increased neurodevelopmental risk and recommend avoidance, while being honest that the causal mechanism remains uncertain.
Clinical Bottom Line
Pregnant women or women planning pregnancy should be counseled that prenatal cannabis use is associated with increased autism risk and should be avoided until we have stronger mechanistic clarity. Clinicians should recognize cannabis as a neurodevelopmental concern marker, not yet proven cause.
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