ABCD Study: Risks to Children From Cannabis During Pregnancy Interview with:
Sarah E. Paul, BA , Graduate Student and
Ryan Bogdan, PhD, Associate Professor
Washington University in St. Louis
St. Louis, MO 63130 What is the background for this study?

Sarah Paul: This study was motivated by several trends in cannabis use, its legal landscape, and people’s perception of risk. As more states legalize recreational cannabis use, cannabis has become more accessible as well as more potent. Over the past couple of decades, the percentage of adolescents and adults who think that cannabis use is risky or harmful has fallen substantially.

Cannabis dispensaries have been reported to actually recommend cannabis to pregnant women for the treatment of pregnancy-related nausea. And finally, between 2002/2003 and 2016/2017, the percentage of women reporting cannabis use during their pregnancies rose 106%. Given these trends and the mixed literature regarding the potential consequences associated with prenatal cannabis exposure, we aimed to comprehensively examine a range of outcomes in a large, representative sample while accounting for a host of important potentially confounding covariates. What are the main findings?

Sarah Paul: We found that when not controlling for these covariates (e.g., family history of psychopathology, SES, prenatal exposure to alcohol and tobacco, among others), those exposed to cannabis after and those exposed only before their moms discovered their pregnancies had higher scores on measures of psychopathology, sleep problems, and BMI, as well as lower birthweight, cognition, and global brain volume metrics relative to those never exposed to cannabis. However, once accounting for potentially confounding variables, only those exposed after maternal knowledge of pregnancy showed higher psychopathology scores than those never exposed. What should readers take away from your report?

Dr. Ryan Bogdan:  These associations were small and these data in no way demonstrate that prenatal cannabis exposure causes these problems in kids – however, they increase the plausibility that prenatal cannabis exposure may contribute to them by showing associations that are independent of confounds. Interestingly the receptors to which THC bind primarily in the brain, the endocannabinoid type 1 receptor, have been linked to neurodevelopment and are not known to be expressed in the fetus prior to 5-6 weeks – it is plausible that associations prior to this time would be attributable to confounding variables while exposure after their expression may not be.  We need experimental non-human animal models, replication in other datasets, and unique study designs (e.g., siblings discordant for prenatal exposure) to better inform causality – in our study the role of unmeasured confounds (e.g., reasons mothers used during pregnancy, paternal germline exposure prior to conception, access to healthcare during pregnancy, increased liability not accounted for) cannot be discounted and it is possible that what we are observing is not caused by prenatal cannabis exposure.

Dr. Ryan Bogdan Notably, in the ABCD Study data, associations with adverse outcomes in children exposed to prenatal cannabis were more robust and consistent than those associated with prenatal exposure to tobacco or alcohol. Highly effective public health campaigns involving public health messaging and attention from healthcare providers may have contributed to substantial reductions in tobacco and alcohol use during pregnancy. However, cannabis use during pregnancy is rising and similar public health messaging and attention from healthcare providers may benefit children.

Dr. Ryan Bogdan: Overall, my take on these data is that cannabis use among pregnant women should be discouraged. As we only observed associations to be independent of potential confounds when exposure occurred after maternal knowledge  if someone has used before knowing they are pregnant, stopping may still benefit offspring. With that said, it is also important that expecting mothers who may be experiencing difficulties are not stigmatized. Stopping substance use is difficult, especially during challenging times such as pregnancy. Physician and psychologist support and empirically-based paradigms aimed at helping pregnant women quit are important. Lastly, couples who are planning on having a child may wish to consider addressing cannabis use before they begin attempting to conceive and pregnancy-related stressors mount.

We do not have any disclosures to report, but we do wish to express our gratitude to the ABCD participants and researchers who gave and collected these valuable data.


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. doi:10.1001/jamapsychiatry.2020.2902 



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Last Updated on September 25, 2020 by Marie Benz MD FAAD