The Epigenetic Impact of Cannabis Use During Pregnancy on Child’s Health

In recent years, the popularity and availability of cannabis has grown significantly, with various consumption methods like edibles gaining traction. However, alongside this trend, there has been a worrisome increase in cannabis use among pregnant women. Unfortunately, our understanding of the detailed effects of using cannabis during pregnancy on the developing child remains limited. Because normal fetal development relies on the crucial process of epigenetic regulation and gene expression modification, it has been suggested that studying the molecular changes linked to cannabis exposure during pregnancy could provide important insights.

To gain a better understanding of the effects of cannabis use during pregnancy, researchers from the Oregon Health & Science University (OHSU) conducted a unique preclinical study that focused on investigating the epigenetic impact of THC, the main active component in cannabis, on fetal development and future health outcomes. The study’s findings were published in the journal Clinical Epigenetics.

With the increasing prevalence of cannabis use, there is a common perception that it is safe. As a result, more pregnant women are turning to cannabis, particularly during the first trimester, to relieve symptoms like morning sickness. However, early pregnancy is a critical time when the developing fetus is most susceptible to environmental factors.

“The reality is that cannabis still carries many health risks for certain populations, including those who are pregnant,” explains Lyndsey Shorey-Kendrick, Ph.D., a computational biologist at OHSU’s Division of Neurosciences.  “If we’re able to better understand the impacts, we can more effectively communicate the risks to patients and support safer habits during the vulnerable prenatal period.”

Cannabis, also known as marijuana, contains a psychoactive component called delta-9-tetrahydrocannabinol (THC). Like other nutrient and chemical substances, THC can pass through the placenta and bind to cannabinoid receptors in the placenta and fetal organs, including the brain.

Limited studies have shown that prenatal exposure to THC in cannabis is associated with adverse effects such as preterm birth, stillbirth, and neurobehavioral issues in offspring. Furthermore, research suggests that exposure to THC during pregnancy can cause changes in DNA methylation in the placenta and the brains of the affected offspring, which may contribute to these negative outcomes.

In previous blog posts, we discussed how THC can affect DNA methylation and lower sperm concentration in animal models. It’s well known that DNA methylation is crucial for child development as it regulates gene expression, ensuring the proper activation of genes. Disruptions in this epigenetic mechanism can lead to developmental abnormalities and increase the risk of disease in children.

The current study was set up to investigate daily cannabis exposure in non-human primates (NHP). Specifically, the researchers examined how THC administered through edibles, a common consumption method, influenced epigenetic changes in crucial areas for fetal development, including the placenta, fetal lung, brain, and heart.

The results showed that THC exposure led to epigenetic changes in all the observed tissue types, with the most pronounced effects seen in the placenta. These changes affected genes related to embryonic development and neurobehavioral disorders like autism spectrum disorder and attention deficit hyperactivity disorder (ADHD) – conditions known to have negative effects on memory, verbal reasoning, hyperactivity, impulsivity, and attention in children and adolescents

Although further research is needed to fully understand the long-term implications of these epigenetic changes, this study enhances our understanding of the underlying mechanisms and neurobehavioral differences observed in children exposed to cannabis during pregnancy.

In addition, the research team hopes their findings will make a valuable contribution to the limited literature on THC use during pregnancy. And play a significant role in guiding patient counseling and shaping future public health policies related to cannabis.

“It’s not common practice for providers to discuss cannabis use with patients who are pregnant or trying to conceive,” says Jamie Lo, M.D., M.C.R., associate professor of obstetrics and gynecology OHSU School of Medicine, and Division of Reproductive and Developmental Sciences at the ONPRC. “I hope our work can help open up a broader dialogue about the risks of cannabis use in the preconception and prenatal period, so we can improve children’s health in the long run.”

Source: Shorey-Kendrick LE. et al. Prenatal delta-9-tetrahydrocannabinol exposure is associated with changes in rhesus macaque DNA methylation enriched for autism genes. Clinical Epigenetics, July 6, 2023.

Reference: Rideout N. THC use during pregnancy linked to changes in fetal development. Oregon Health & Science University. July 6, 2023.