Marijuana Effects: One-Time Exposure In Early Pregnancy May Cause Birth Defects

Exposure to marijuana during pregnancy may have serious effects on the developing fetus. Researchers found the drug could put babies at risk of growth issues, such as brain and facial birth defects.

The new study, published in the journal Scientific Reports, analyzed the effects of marijuana compounds, CBD and THC, on early pregnancy. Researchers said the drug appeared with very similar effects seen in babies exposed to alcohol in the womb.

The team tested marijuana effects on mice. They said the animal study offers very accurate models for the development of the embryo during early pregnancy.

The animal subjects received either cannabinoids or alcohol or both on day eight of pregnancy. This stage is similar to the third and fourth weeks of pregnancy in humans. 

"The development of the embryo in this time period is very similar across all vertebrates," Scott Parnell, senior study author and an assistant professor of cell biology and physiology in the University Of North Carolina School of Medicine, said in a statement. "In this study we also test a synthetic cannabinoid in zebrafish that yielded similar growth deformations as the natural CBs."

Researchers said the amounts of CBD and THC provided were within the therapeutic or safe range for humans. Results showed that one-time exposure to the marijuana compounds caused negative effects on babies. 

However, when combined the drug with alcohol, the risk of brain and facial birth defects more than doubled. Researchers explained that CBD and THC potentially disrupted signaling between molecules and cells that control growth and development during pregnancy. 

"The interaction between alcohol and CBs we witnessed is very concerning," Eric Fish, study author and a research associate in the UNC School of Medicine Bowles Center for Alcohol Studies, said. "Previous studies have shown that CBs and alcohol are frequently used together, and for pregnant women we're learning that could be very dangerous to a developing child."

The researchers plan to continue the study to further understand the long-term effects of exposure to marijuana. The team also wants to mimic real-life usage in human pregnancy.

Parnell said the study raised concerns that common marijuana products, like CBD oil, may have negative effects on women and babies during pregnancy. 

Marijuana This photograph taken on April 22, 2019, shows a type of cannabis in a bag at Cremers Coffee Shop in The Hague. Robin Van Lonkhuijsen/AFP/Getty Images