We look at the data.
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Marijuana is the most commonly used illicit substance among expecting mothers. And according to some studies, marijuana use during pregnancy is on the rise for everything from nausea to stress.
One recent study conducted in California asked pregnant women to report their marijuana use in the past month and found a 1.5% increase in reported use between 2002 and 2014. (Many of the mothers who had reported smoking in the last month had done so during the first trimester before they knew they were pregnant.)
According to some studies, this increased marijuana use during pregnancy could result in health problems for newborns. One study conducted in Australia found that marijuana use during pregnancy was associated with lower birth weights for the mothers’ babies. Another study, published in the American Journal of Obstetrics and Gynecology, points to evidence that marijuana use during pregnancy can affect a child’s neurological development.
But advocates of marijuana use during pregnancy are skeptical of these studies—and for good reason. As the study published in the American Journal of Obstetrics and Gynecology soberly admits: “Existing studies are plagued by confounding tobacco and other drug exposures as well as sociodemographic factors.” In other words, while the data suggests that marijuana use during pregnancy could have adverse effects on a mother’s child, this data itself wasn’t produced under ideal circumstances.
One study, conducted in Jamaica, even found that the 30-day-old babies of mothers who had consumed marijuana during pregnancy “had more favorable scores” on reflex and autonomic stability tests. Another study, published in the Obstetrical & Gynecological Survey, is somewhat indecisive. “The current evidence suggests subtle effects of heavy marijuana use on developmental outcomes of children,” reads the study’s abstract. “However, these effects are not sufficient to warrant concerns above those associated with tobacco use.”
Again, this study found that even heavy marijuana use only produced “subtle” effects on pregnant women’s children. As advocates of marijuana use during pregnancy point out, even over-the-counter drugs once considered safe can be later found to produce unwanted side effects. In 2013, for example, a study found that Diclectin, one of the most popular morning sickness drugs, may be tied to birth defects.
According to Dr. Jordan Tishler, an M.D. from Harvard who now specializes in medical cannabis, one of the main arguments made by advocates of marijuana use during pregnancy is that “whatever might or might not be wrong with using cannabis is probably nothing compared to how sick women can be while they’re pregnant, and the harm of pharmaceutical options.” “On some level,” he says, “they have a point.”
But while some legal pharmaceutical medications can have negative outcomes on a pregnant woman’s child, Tishler says, there are still a number of pharmaceutical options for which “we have a lot of data and a lot of experience using them and knowing that they are at least relatively safe.” Comparatively, the research on marijuana use during pregnancy is scarce.
“There are definitely not enough high-quality and well-controlled studies available yet for us to understand the effects of marijuana use during pregnancy—or breastfeeding—on a fetus or baby,” Julia Dilley, a senior research scientist and epidemiologist at the Oregon Health Authority, tells Herb. “We have good evidence that THC and other cannabinoids pass through the placenta and are found in breastmilk, so babies are exposed if the mother uses; we don’t know what happens as a result.”
One challenge to getting these answers, however, is that conducting rigorous trials on pregnant women can be both bureaucratically difficult and dangerous. According to Dr. Robyn Horsager-Boehrer, a professor of Obstetrics and Gynecology at UT Southwestern Medical Center “because of the suggestion that exposure [to marijuana] in animals is detrimental, I think it is highly unlikely that institutional review boards would approve this type of study in pregnancy—or that we could recruit patients into the study.”
In other words, not only does marijuana’s Schedule I status under the Controlled Substances Act make it extremely difficult to study in general, but testing the effects of marijuana use during pregnancy in a live trial would be a dubious proposition under any legal circumstances. And without firm evidence, these experts agree, it’s best to air on the side of caution.
“While nausea and vomiting is an unpleasant side effect of early pregnancy, for the majority of cases it does not cause harm to the fetus or mother. There is a very small portion of patients who do suffer more significant consequences,” says Horsager-Boehrer. “That being said, it can be pretty miserable.”
This misery during pregnancy, according to these experts, is better than regret if something does go wrong due to marijuana use. “There’s often times a lot of guilt associated with bad outcomes,” says Tishler. “Now, if you’re going to say against medical advice ‘I’m going to use cannabis during pregnancy,’ that’s kind of a set up for when something goes wrong, blaming yourself for it.”
There is disagreement as to what policies should exist to address the increase of marijuana use during pregnancy. Some states, like Alabama, have a history of punishing marijuana use during pregnancy with jail time. In Arizona, lawmakers originally wanted to implement a wholesale ban on medical marijuana for pregnant women, but ended up requiring warning signs about the potential risks of marijuana use during pregnancy in dispensaries instead.
In Tishler’s view, once the risks of marijuana use during pregnancy are made known, the decision should be left to the expecting-mother herself as to how she wants to proceed. “You know we’re never going to control, and shouldn’t attempt to really control people’s behavior, because the only way to do that is punitive and that’s what we’re trying to get away from,” says Tishler. “We don’t want to incarcerate pregnant women, right?” Instead, Tishler suggests taking a more proactive approach by introducing informative ad campaigns, modifying marijuana packaging to include warning labels, and most importantly, putting a greater emphasis on education.