An updated review found no unique pattern of birth defects from prenatal cannabis exposure, though some studies reported increased gastroschisis risk. Long-term effects included impaired attention and memory, increased depression and anxiety, and delinquency.
Pregnant individuals, OB-GYN providers, and developmental researchers.
Attention and memory specifically affected; no unique birth defect pattern
What the researchers found
Prenatal cannabis exposure was not associated with a unique pattern of birth defects or reductions in global IQ, but specific cognitive skills (attention and memory) were negatively affected. Long-term impacts included increased depressive symptoms, anxiety, and delinquency. Infant exposure through breast milk appeared relatively low.
Why it matters
Cannabis use during pregnancy is increasing as legalization spreads and perceived risk decreases. The evidence of specific cognitive and psychological effects, rather than gross birth defects, highlights subtle risks that may not be immediately apparent.
The numbers in context
THC levels in cannabis products are increasing. Specific cognitive domains affected: attention and memory. Psychological outcomes: increased depression, anxiety, and delinquency. Infant exposure via breast milk described as relatively low compared to maternal exposure.
How the study worked
Narrative review summarizing epidemiological studies on cannabis use during pregnancy and lactation, including data on congenital anomalies, fetal growth, cognitive development, and psychological outcomes.
What this study cannot tell us
Most existing studies have limited ability to quantify actual THC exposure. Confounders (tobacco, alcohol, socioeconomic factors) are difficult to fully control. The review notes that weaknesses in past research make definitive conclusions challenging.
How to read the evidence
Moderate: comprehensive narrative review synthesizing multiple epidemiological studies, though limited by the weaknesses of underlying research.
When this study was published
Published in 2020 in Birth Defects Research.
The bigger picture
As THC potency continues to increase, the gap between historical research and current exposure levels grows. Prospective birth cohort studies with biological sample collection are needed to establish reliable risk estimates for modern cannabis products.
Questions still open
- How do higher THC concentrations in modern products affect fetal outcomes compared to older studies? At what gestational period is the fetus most vulnerable? Are attention deficits from prenatal exposure permanent or reversible?
Common questions
Does cannabis cause birth defects?
Is it safe to use cannabis while breastfeeding?
Read the original research
Update on the developmental consequences of cannabis use during pregnancy and lactation.
Birth defects research, 112(15), 1126-1138
Citation
Grant, Kimberly S; Conover, Elizabeth; Chambers, Christina D. (2020). Update on the developmental consequences of cannabis use during pregnancy and lactation.. Birth defects research, 112(15), 1126-1138. https://doi.org/10.1002/bdr2.1766
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