In a study using pregnant monkeys, researchers found that Cannabis use during pregnancy could potentially affect fetal brain development leading to changes associated with neurobiological disorders like autism and ADHD.
According to the NIH, cannabis use among pregnant individuals in the United States more than doubled from 2002 to 2017. Though reports suggest some people use the drug to help tame morning sickness, 2022 research found links between cannabis exposure during pregnancy and an increased rate of depression, anxiety, and other mental health conditions in children.
Because of the potential health effects, the FDA strongly advises against using any form of cannabidiol (CBD), tetrahydrocannabinol (THC), and cannabis during pregnancy or while breastfeeding.
Still, scientists aren't certain whether prenatal cannabis use impacts children's long-term health.
To investigate this further, Oregon Health & Science University researchers conducted a study using rhesus monkeys to determine whether exposure to THC during pregnancy had long-term health effects on offspring.
The scientist's previous 2022 research showed that THC exposure may negatively impact placental function. However, their latest work, published on July 6 in Clinical Epigenetics, revealed that THC exposure during pregnancy alters the placental and fetal epigenome, causing changes consistent with neurobehavioral conditions like autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD).
To conduct the research, the team fed pregnant rhesus monkeys a daily edible containing THC or a placebo. Then, the researchers evaluated epigenetic changes in the placenta and fetal tissues, including the heart, lungs, and two areas of the brain.
They found that exposure to THC altered the epigenome in all five tissues examined. The scientists say that alterations in the epigenome can change how genes are transformed into a function or trait.
In addition, prenatal THC exposure altered placental and fetal DNA methylation at genes involved in neurobehavioral development. Moreover, the placental gene changes in THC-exposed monkeys showed similarities to human placentas from pregnancies where the newborn was later diagnosed with ASD.
The researchers say that these findings, along with their previous research results, suggest that prenatal THC exposure dysregulates placental gene expression and function through effects on the epigenome— which may impact brain development.
Still, the team notes that these results found in monkeys do not prove that prenatal cannabis exposure is a cause or a risk factor for the development of ASD. However, it does add biological evidence to support a previous Canadian study that found an association between maternal cannabis use in pregnancy and an increased incidence of ASD in offspring.
"As the prevalence of prenatal cannabis use is rising along with significant increases in potency, there is an urgent need for evidence-driven recommendations on the safety of use both prenatally and postnatally," the study authors wrote.
In addition, the authors hope these findings help guide patient counseling and public health policies focused on prenatal cannabis use in the future to improve children’s long-term health.
- NIH. Study finds increased cannabis use during pregnancy.
- NPR. Some Pregnant Women Use Weed For Morning Sickness But FDA Cautions Against It.
- NIH. Prenatal cannabis exposure associated with mental disorders in children that persist into early adolescence.
- Scientific Reports. Chronic prenatal delta-9-tetrahydrocannabinol exposure adversely impacts placental function and development in a rhesus macaque model.
- Clinical Epigenetics. Prenatal delta-9-tetrahydrocannabinol exposure is associated with changes in rhesus macaque DNA methylation enriched for autism genes.