Is it OK to use cannabis while pregnant?

Contrary to many blogged opinions and dubious advice, there’s no safe amount of cannabis exposure for babies in the womb. Prenatal exposure to cannabis could harm children by affecting their birth size, adolescent behavior and chances of developing psychosis.

Studies since the 1970s have backed up this health alert. More recently, Dr. Nathaniel DeNicola of George Washington University told Reuters: “We have sufficient data and biologic plausibility that marijuana use during pregnancy increases the risk of preterm birth and growth restricted babies.”¹

In May 2018, researchers at the University at Buffalo Research Institute on Addictions found prenatal cannabis use can have consequences on infants’ weight and can influence behavior problems, especially when combined with tobacco use.

Infants who had been exposed to both tobacco and cannabis, “...especially into the third trimester, were smaller in length, weight and head size, and were more likely to be born earlier, compared to babies who were not exposed to anything,” a press release states.²


Another 2018 study reported prenatal exposure to THC could lead to “subtle, persistent changes in targeted aspects of higher-level cognition and psychological well-being.”³

The perception of how cannabis use influences offspring needs to be overhauled, due to research that found that 70 percent of both pregnant and non-pregnant women think using cannabis once or twice a week during pregnancy has little or no risk. ⁴

Also alarming is a recent survey that found 70 percent of 400 Colorado cannabis dispensaries advised a woman who claimed to be pregnant and suffering from morning sickness to use cannabis to treat her ailment.⁵

While there have been conflicting results on how harmful cannabis can be for pregnant women, a “better safe than sorry” approach is the prudent decision.

Even if you know how the placenta is designed to prevent harmful molecules in the mother’s body from infecting the fetus, it’s critical to recognize that more research needs to be conducted on the exact ways cannabis influences the fetus. The results have been coming in drips, rather than waves, but with legalization taking hold in Canada and in several U.S. states, we can expect more academic researchers to now access cannabis without fear of arrest.

Kelly Young-Wolff, Research Scientist at Kaiser Permanente Northern California, has conducted several studies on cannabis use by pregnant women, and she says in an interview that one study concluded, “...the prevalence of marijuana use in pregnancy was increasing more rapidly among adolescents and young adults.”⁶

She goes on to stress how U.S. national guidelines, “...strongly recommend that clinicians screen for and advise against marijuana use during pregnancy due to evidence of lower offspring birthweight and increased risk of developmental problems.”

Young-Wolff knows public perception can often be shaped by scientific evidence, which is why she adds: “There is also an urgent need to understand the health effects of prenatal marijuana use and use of marijuana during breastfeeding, and to test whether the legalization of marijuana is associated with further increases in marijuana use during pregnancy.”