• Posted July 11, 2023

Monkey Study Suggests Hazards of Marijuana Use During Pregnancy

Marijuana use during pregnancy may impact the baby's brain development and long-term health, according to new research with monkeys.

THC (delta-9-tetrahydrocannabinol) -- the main psychoactive ingredient in cannabis -- altered the placental and fetal epigenome in monkeys who were given THC edibles, researchers say. These modifications can cause changes that affect the way genes work.

Such changes to gene regulation and expression are like those seen with common neurobehavioral conditions, including autism spectrum disorder and attention deficit hyperactivity disorder, the researchers said. However, they did not say cannabis caused those disorders.

“Cannabis is one of the most commonly used drugs and is widely available across the country, so there is a common perception that its completely safe to use,” said study lead author Lyndsey Shorey-Kendrick, a computational biologist at Oregon Health & Science University's Oregon National Primate Research Center.

“The reality is that cannabis still carries many health risks for certain populations, including those who are pregnant,” Shorey-Kendrick said in a school news release.

Cannabis use in pregnancy is rapidly increasing, especially during the first trimester, when people may use it to reduce the effects of morning sickness, the study noted.

"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,” Shorey-Kendrick added.

To study the effects, researchers administered THC in a daily edible to monkeys and then compared the effects to those in a group that received a placebo. They evaluated the placenta and fetal lungs, brain and heart, key areas that indicate healthy prenatal development.

While studies on animals don't always have the same results in humans, the researchers found that THC exposure altered the epigenome -- that's the process or compounds that affect the gene and turns this information into observable traits. Any impact on epigenetic processes due to drug exposure is concerning, especially during a critical developmental window such as pregnancy, according to the study.

“It's not common practice for providers to discuss cannabis use with patients who are pregnant or trying to conceive,” said study co-author Dr. Jamie Lo, an associate professor of obstetrics and gynecology at OHSU School of Medicine. “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.”

The preclinical study was published July 6 in the journal Clinical Epigenetics.

The research was supported by divisions of the U.S. National Institutes of Health, the March of Dimes and others.

More information

The U.S. National Library of Medicine has more on fetal development.

SOURCE: Oregon Health & Science University, news release, July 6, 2023