In a cohort of nearly 120,000 pregnancies, maternal cannabis use in early pregnancy was not associated with increased risk of speech/language disorders, motor delays, or global developmental delays in children through age 5.5 years.
Pregnant individuals, pediatricians, developmental researchers
No association at any use frequency
What the researchers found
No association was observed between maternal prenatal cannabis use and child speech/language disorders (HR 0.93, 95% CI 0.84-1.03), global developmental delays (HR 1.04, 95% CI 0.68-1.59), or motor delays (HR 0.86, 95% CI 0.69-1.06). No dose-response relationship was found.
Why it matters
While prenatal cannabis has been linked to neonatal outcomes like low birth weight, evidence on longer-term developmental effects has been limited and conflicting. This large study found no association with early developmental delays.
The numbers in context
119,976 pregnancies among 106,240 individuals. 6,778 (5.6%) had documented cannabis use. Daily use: 618 (0.5%). Weekly: 722 (0.6%). Monthly or less: 1,617 (1.3%). No significant associations at any frequency.
How the study worked
Retrospective cohort of 119,976 children born 2015-2019 at Kaiser Permanente Northern California, followed to age 5.5 years. Prenatal cannabis use screened via self-report and urine toxicology at ~8-10 weeks gestation. Developmental delays identified from ICD-9/10 codes in electronic health records.
What this study cannot tell us
Cannabis use assessed only at entry to prenatal care (~8-10 weeks), missing later-pregnancy use patterns. Some developmental delays may not manifest until after age 5.5. Self-report likely underestimates use. EHR diagnosis codes may miss milder delays.
How to read the evidence
Large population-based cohort with objective screening and EHR follow-up provides strong evidence, though limited to early-pregnancy exposure assessment.
When this study was published
2024 study of Kaiser Permanente data from 2015-2021
The bigger picture
This null finding contrasts with studies linking prenatal cannabis to ASD or ADHD, suggesting different developmental outcomes may have different risk profiles. The authors note this does not mean prenatal cannabis is safe, given known associations with other adverse outcomes.
Questions still open
- Would longer follow-up (through school age) reveal associations not apparent by age 5.5? Do specific developmental domains show effects at later ages?
Common questions
Does this mean cannabis is safe during pregnancy?
How was cannabis use measured?
Read the original research
Early Maternal Prenatal Cannabis Use and Child Developmental Delays.
JAMA network open, 7(10), e2440295
Citation
Avalos, Lyndsay A; Oberman, Nina; Alexeeff, Stacey E; Croen, Lisa A; Davignon, Meghan N; Adams, Sara R; Ansley, Deborah; Chambers, Christina D; Steuerle, Kristin; Young-Wolff, Kelly C. (2024). Early Maternal Prenatal Cannabis Use and Child Developmental Delays.. JAMA network open, 7(10), e2440295. https://doi.org/10.1001/jamanetworkopen.2024.40295
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