Using marijuana during pregnancy could have an affect on a gestating infant’s brain, a new study has revealed. The cannabis study, led by researchers at the Karolinska Institute in Sweden and the Medical University of Vienna in Austria and published online in the EMBO Journal, was conducted on mice and brain tissue from human fetuses.

The study found that THC (delta-9-tetrahydrocannabinol), the active ingredient present in marijuana, interfered with the development of connections in the brain of a fetus. Researchers discovered that THC exposure to a baby in the womb affected the creation of connections between nerve cells located in the cerebral cortex, the region of the brain responsible for the creation of memories and the execution of high-level cognitive skills.

Researchers observed the effects of marijuana on a developing brain by exposing growing mice brain cells to THC, injecting pregnant mice with THC, and observing the brains of fetuses that were voluntarily aborted and whose mothers had smoked marijuana during pregnancy.

Neuroscientist Tibor Harkany, lead researcher in the cannabis study, says that while the effects of marijuana on a fetus’ brain are not known on a molecular level, any drug that interferes with the development of a fetus could be harmful, and that effects of marijuana exposure to an infant  “could even last into adulthood,” reported the Huffington Post.

Health experts, as well as Harkany, advise that marijuana use, even for medical purposes, should be avoided while pregnant.

Krysta is a writer and researcher with Ring of Fire. Follow her on Twitter @KrystaLoera.