Ira J. Chasnoff, M.D.

Ira J. Chasnoff M.D.

Aristotle's Child

The Truth about Marijuana and Pregnancy

Pregnancy testing should be required before a marijuana prescription is written.

Posted Nov 12, 2011

I recently received this email from one of my readers:

I am about to be a father and have been told that you have done research on the effects of marijuana use during pregnancy on a child. I would like to know where I can find and read whatever has been published about these studies.

The topic of marijuana use in pregnancy is a very confusing one, mainly because marijuana does not have a direct health effect on pregnancy; there is no increased rate of preterm labor, growth retardation, or other such complications. However—and this is a big however—even though marijuana does not affect pregnancy outcome, it does have an impact on fetal brain development. 

Long-term studies document that children whose mothers have used marijuana during pregnancy have a higher rate of executive functioning difficulties, which interfere with learning and behavior, especially as related to planning and following through with a task. Executive functioning is a vital issue, because although the children "look normal," they cannot behave and respond appropriately in the classroom or sometimes even at home. For a fuller discussion of executive functioning, see my previous blog on this topic.

The "medical marijuana" movement complicates things further. Marijuana does have a role in treating some conditions, especially alleviating the side effects of chemotherapy. However, few if any states that have legislated the availability of medical marijuana have included guidelines for prescribing marijuana to pregnant women.

In studies that we have conducted in states that have medical marijuana laws, we find that the rates of marijuana use in pregnancy are some of the highest in the nation. As I noted earlier, this can have a profound effect on the children's long-term outcomes.

At the least, any woman of childbearing age who requests a prescription for marijuana should have a pregnancy test prior to being given a prescription. I'm sure there are those who would disagree with this approach, but there is enough scientific evidence to demand some restriction of medicinal use during pregnancy.  

Bottom line—marijuana use is not safe in pregnancy. We need to get that message out to the public and to legislators.

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