Review finds prenatal cannabis exposure linked to attention problems and later psychological issues, not birth defects
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.
Quick Facts
What This Study 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.
Key Numbers
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 They Did This
Narrative review summarizing epidemiological studies on cannabis use during pregnancy and lactation, including data on congenital anomalies, fetal growth, cognitive development, and psychological outcomes.
Why This Research 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 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.
What This Study Doesn't 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.
Questions This Raises
- ?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?
Trust & Context
- Key Stat:
- Attention and memory specifically affected; no unique birth defect pattern
- Evidence Grade:
- Moderate: comprehensive narrative review synthesizing multiple epidemiological studies, though limited by the weaknesses of underlying research.
- Study Age:
- Published in 2020 in Birth Defects Research.
- Original Title:
- Update on the developmental consequences of cannabis use during pregnancy and lactation.
- Published In:
- Birth defects research, 112(15), 1126-1138 (2020)
- Authors:
- Grant, Kimberly S, Conover, Elizabeth, Chambers, Christina D(5)
- Database ID:
- RTHC-02582
Evidence Hierarchy
Summarizes existing research on a topic.
What do these levels mean? →Frequently Asked Questions
Does cannabis cause birth defects?
No unique pattern of birth defects has been linked to cannabis exposure, though some studies reported increased risk of gastroschisis (an abdominal wall defect). The more concerning findings involve subtle cognitive effects that emerge later in childhood.
Is it safe to use cannabis while breastfeeding?
While the review notes that infant exposure through breast milk appears relatively low compared to maternal levels, the data are limited. THC is fat-soluble and does transfer into breast milk, so risks cannot be excluded.
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Cite This Study
https://rethinkthc.com/research/RTHC-02582APA
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
MLA
Grant, Kimberly S, et al. "Update on the developmental consequences of cannabis use during pregnancy and lactation.." Birth defects research, 2020. https://doi.org/10.1002/bdr2.1766
RethinkTHC
RethinkTHC Research Database. "Update on the developmental consequences of cannabis use dur..." RTHC-02582. Retrieved from https://rethinkthc.com/research/grant-2020-update-on-the-developmental
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.