What might happen to a fetus exposed to cannabis in utero?

Fish EW, Murdaugh LB, Zhang C, Boschen KE, Boa-Amponsem O, Mendoza-Romero HN, Tarpley M, Chdid L, Mukhopadhyay S, Cole GJ, Williams KP, Parnell SE. Cannabinoids exacerbate alcohol teratogenesis by a CD1-Hudgehog interaction. Scientific Report 2019;9:16507

The original article abstract can be found on the Nature website

The National Institute on Alcohol Abuse and Alcoholism also published a summary on their website

Why was this study conducted?

Data from the U.S. suggests that exposure to cannabis among pregnant women may be increasing, either alone or in combination with alcohol. The teratogenic (relating to or causing developmental malformation) effects of alcohol during pregnancy have been well documented, but much less is known about the risk posed by cannabis.

What does this study add?

Researchers administered different doses of a variety of cannabinoids, including cannabidiol (CBD) and tetrahydrocannabinol (THC), to mice, either alone or in combination with low or high doses of alcohol. Administration occurred on day eight of pregnancy, which corresponds to the third and fourth week of human pregnancy, and in amounts equivalent to what would be considered a medicinal therapeutic dose in humans. One-time exposure to CBD and THC was associated with eye, brain and facial malformations similar to those caused by alcohol exposure. When mice were given both cannabinoids and alcohol, the likelihood of birth defects more than doubled. Results were validated using a zebrafish model. The craniofacial and brain defects observed in both species were similar to what occurs when there is impaired signaling of the Sonic Hedgehog (Shh) gene, a protein that is essential for embryonic development and plays a role in cell growth, cell specialization, and the normal shaping of the body. Cannabinoids appear to reduce Shh signaling by inhibiting a protein encoded by the Smoothened (Smo) gene.

Is there anything else I should know?

This study has provided important insights into the potential mechanism by which cannabis, alone or in combination of alcohol, increases the risk of birth defects if consumed by women early in their pregnancy. This is important information for physicians and women who are pregnant or considering pregnancy.