The Impact of Maternal Marijuana Use On the Fetal Brain

a brief review of data from Fall of 2020

By Dr. WIlliam Stigall

7 December 2020

As you know, the American College of Pediatricians considers the increasing prevalence of marijuana usage and its legalization to be detrimental to children and families. The ACPeds has issued several position statements on this issue including Marijuana and Mental IllnessMarijuana Use: Detrimental to Youth, and the Effect of Marijuana Legalization on Risky Behavior

As an update, ACPeds calls attention to two recently published articles that further fortify our position in favor of prohibiting recreational marijuana use.

The first article entitled, "Associations Between Prenatal Cannabis Exposure and Childhood Outcomes: Results From the ABCD Study,” was published in JAMA Psychiatry in September 2020. It assesses the impact of prenatal exposure to marijuana and mental and physical health for children at age 10 years old. This is a large study involving over 11,000 children, with 655 exposed to marijuana prenatally. The study looks at differences between children not exposed to marijuana, children exposed only until their mothers learned they were pregnant, and children who continued to be exposed even after their mothers learned they were pregnant.  

Compared to those never exposed, marijuana-exposed children had increased psychotic-like experiences, problems in internalizing, externalizing, attention, cognition, sleep, and weight. Children whose mothers continued to use marijuana after learning they were pregnant fared the worst across all metrics and suffered from additional pathologies including lower birth weight, decreased brain volume, and decreased cerebral white matter volume.1  

In addition, the paper’s first reference is also worth reading. It is a 2018 review from Nature Neuropsychopharmacology, entitled, "US Epidemiology of Cannabis Use and Associated Problems.” The authors conclude that recent trends in marijuana legalization and public acceptance have led to "national increases in cannabis potency, prenatal and unintentional childhood exposure; and in adults, increased use, CUD (Cannabis Use Disorder), cannabis-related emergency room visits, and fatal vehicle crashes." 

The second paper to bring to your attention was published in Nature Medicine in October 2020 and is entitled, "Maternal cannabis use in pregnancy and child neurodevelopmental outcomes”. It involves a much larger sample - all live births in Ontario between 2007 and 2012 yielding over 500,000 children. This study also found significantly worse outcomes in neurodevelopment metrics including autism, learning disorders, and ADHD. Notably, children exposed to marijuana in utero had at least a 50% increased risk of Autism. The article is very good, as is the editorial accompanying the paper, "The importance of generating more data on cannabis use in pregnancy”. 

It is clear and is only becoming clearer that the increased marijuana use among adults due to legalization is detrimental not only to the adult users but also to children and families at large. Where recreational marijuana has been legalized, the American College of Pediatricians urges policymakers to reinstate prohibitions. In states that currently ban recreational marijuana use, we urge leaders to uphold those health-preserving and life-saving laws. Our society must always strive for what is best for children. 


1.  Paul SE, Hatoum AS, Fine JD, et al. Associations Between Prenatal Cannabis Exposure and Childhood Outcomes: Results From the ABCD Study. JAMA Psychiatry. Published online September 23, 2020. 

2.  Hasin, D. US Epidemiology of Cannabis Use and Associated Problems. Neuropsychopharmacol. 43, 195–212 (2018). Available at Accessed November 13, 2020.

3.  Corsi, D.J., Donelle, J., Sucha, E. et al. Maternal cannabis use in pregnancy and child neurodevelopmental outcomes. Nat Med 26, 1536–1540 (2020).

4.  Bérard, A. The importance of generating more data on cannabis use in pregnancy. Nat Med 26, 1515–1516 (2020).

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