A 2020 study entitled "Totality of the Evidence Suggests Prenatal Cannabis Exposure Does Not Lead to Cognitive Impairments: A Systematic & Critical Review" that was published in the journal Frontiers in Psychology investigated if cannabis consumption among pregnant women may lead to cognitive impairment among their children.
The study's authors noted that there is limited data "demonstrating pronounced negative effects of prenatal cannabis exposure." Despite this, "popular opinion and public policies still reflect the belief that cannabis is [toxic to a human fetus]."
This research, designed as a review of previous "longitudinal studies examining the impact of prenatal cannabis exposure on multiple domains of cognitive functioning in individuals aged 0 to 22 years" was conducted using PsycINFO, PubMed, and Google Scholar. Studies were included in the review only if they explored "the cognitive performance of offspring exposed to cannabis in utero."
The study determined that the performance of children exposed to cannabis prenatally "did not differ from non-exposed children on the majority of cognitive outcomes."
A total of 1,604 articles were identified in the initial search, of which 184 were chosen for full text review after exclusion of irrelevant studies based on title, abstract, keywords, and/or results," explained the study's authors.
In the end, 45 studies were "deemed appropriate for this review based on inclusion criteria." The final studies reviewed ranged in sample size from only nine to 538 participants. The duration of the studies considered varied from two months to 22 years.
The study determined that prenatal cannabis exposure "was associated with few effects, negative or positive." It reported that the performance of children exposed to cannabis prenatally "did not differ from non-exposed children on the majority of cognitive outcomes."
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The study explained how, in some cases, "intense stigma has resulted in removal of children from their families and even in maternal incarceration" with the rationale that prenatal cannabis exposure "causes persistent deleterious effects, especially on cognitive functioning." However, the data analyzed by this study suggest that such attitudes "should be reevaluated to ensure that our assumptions do not do more harm than the drug itself."
"Despite analyzing studies spanning approximately three decades, we conclude the evidence does not support an association between prenatal cannabis exposure and clinically relevant cognitive deficits."
"Despite analyzing studies spanning approximately three decades, we conclude the evidence does not support an association between prenatal cannabis exposure and clinically relevant cognitive deficits," concluded the scientists.
View the original study.