Adverse effects of prenatal marijuana exposure

The APA Monitor (April/May 2022) summarizes a recent study in the Proceedings of the National Academy of Sciences. The longitudinal study of 322 mother-child pairs began in 2009 with researchers examining placental gene expression, physiology, and early childhood behavior and emotional functioning. Mothers who self-reported cannabis use had young children with higher anxiety, aggression, hyperactivity, and cortisol levels. They also did RNA sequencing in a small subsample finding a relationship between self-reported cannabis use and “lower expression of immune activating genes, including pro-inflammatory cytokines, which are involved in protecting against pathogens. The cannabis-related suppression of several placental immune-gene networks predicted higher anxiety and hyperactivity in this subset.”

There are lots of questions we can ask about these findings. First, we know that pregnant women may self-medicate with cannabis during pregnancy because they think it is safer than medications that treat anxiety and hyperactivity. Thus, anxious and hyperactive moms may more often use cannabis. Second, we don’t know how and how much cannabis they were using. It would be far better if there were more direct measures of cannabis use. Third, we don’t know how this group of mothers compare with mothers in 2022 who may be using cannabis. As I have mentioned before, because cannabis is now legal in many areas, it’s easy to believe that more pregnant women are using cannabis. 

What is scary to me is the biochemical data suggesting that cannabis suppresses pro-inflammatory cytokines and the suppression of immune-gene networks predicted higher anxiety and hyperactivity. This is an area where we clearly need more research.