Dangers/safety of cannabis in pregnancy and breastfeeding

How does it compare with traditional medications?

Cannabis has been used to treat pregnancy related symptoms, such as morning sickness, for millennia. It is quite effective at treating these. This practice has recently, rapidly been growing with legalization. Cannabis is currently used by between 3 and 16 percent of pregnant women in the United States. One study shows a 64 percent increase in maternal cannabis use from 2001 to 2016. Cannabis during pregnancy has largely been frowned upon by medical doctors, who worry about harms such as low birthweight babies, or behavioral difficulties as these children grow up. Many cannabis advocates believe the plant to be natural and largely harmless.

How safe or unsafe is cannabis use during pregnancy and breastfeeding?

Contradictory, anemic evidence

It is difficult to study pregnant women because is unethical to test things out on them. You can’t just give some women a drug, give others a placebo, and see which group has more birth defects. This is against our code of “do no harm”. Consequently, most of the studies on dangers of cannabis during pregnancy are inferential and speculative, with researchers going back in time to see if there are differences between populations of users and non-users. Often, the studies didn’t account for other variables that could have affected perinatal outcomes such as tobacco, poverty, alcohol, educational level, and other drug use. All these factors, if you don’t account for them, can inflate the perceived harms of cannabis because they might contribute to any problems that may appear to be caused by cannabis. For example, poor people have worse health outcomes and, if they use more cannabis, it will look like the cannabis caused these outcomes, rather than just being associated with them.

Of course, this doesn’t mean that cannabis IS safe during pregnancy, just that the studies aren’t conclusive. Another reason it has been difficult to assess the actual harms is that many of the studies were conducted during our War on Drugs where the harms of cannabis, as well as of many other drugs and potential medicines, were flagrantly exaggerated. If ever there were a topic where the merits of the science must be disentangled from the political and social history, it is cannabis.