A growing number of pregnant women are using marijuana or other cannabis products, and a new study suggests that relief of symptoms such as morning sickness may be a primary reason.
In recent years, studies have documented a rise in cannabis use during pregnancy. One U.S. government study found that between 2002 and 2017, the number of pregnant women who said they’d used marijuana in the past month doubled — from about 3.5% to 7%.
But the reasons they choose to use marijuana have not been clear.
So for the new study, researchers did in-depth interviews with 52 pregnant or breastfeeding individuals who had used various cannabis products before pregnancy — not only smoked marijuana, but other products like edibles.
Of that group, 30 continued to use cannabis after becoming pregnant. And nearly all said it was to help manage symptoms, most often morning sickness.
That’s an important point for obstetricians and other health care providers to know, said lead researcher Meredith Vanstone of McMaster University in Hamilton, Ontario, Canada.
“I do worry that providers often think that these are people who just don’t care — that they are using cannabis for fun and could stop if they wanted,” Vanstone said.
“That is not what we found,” she said.
In general, the study participants were well-informed on the evidence, or lack of it, and made a deliberate choice on whether to continue using cannabis during pregnancy, Vanstone noted.
That is not to say that cannabis is a good option for managing morning sickness.
In fact, medical groups such as the American College of Obstetricians and Gynecologists (ACOG) advise against using cannabis for any reason during pregnancy or breastfeeding.
Much of that has to do with the unknowns, the groups say. Some studies have linked mothers’ marijuana use during pregnancy to an increased risk of preterm birth, low birth weight, and learning and attention problems in their children.
Those studies do not prove marijuana is to blame — in part because it is difficult to separate any effects of marijuana from cigarette smoking and drinking, which commonly go together.
And much less is known about other cannabis products that have become popular in recent years, like edibles and cannabidiol (CBD), said Christina Chambers, a professor at the University of California, San Diego.
Now that marijuana is legal in many U.S. states, there is renewed interest in the potential effects of prenatal use, said Chambers, who is also program director of MotherToBaby California.
MotherToBaby is a nonprofit that offers science-based information on the safety of medications and other exposures during pregnancy.
“We need more research,” Chambers said. “The best advice we have now, in the absence of high-quality data, is to avoid (using cannabis) during pregnancy and breastfeeding.”
When it comes to breastfeeding, there is little research on whether a mom’s cannabis use can affect the baby. But, Chambers noted, it’s known that THC — the ingredient responsible for marijuana’s “high” — can cross into breast milk.
“If I were counseling a pregnant person,” Vanstone said, “I would encourage a discussion about the alternatives for symptom management that we know are safe.”
To deal with morning sickness, ACOG recommends starting with diet and lifestyle changes, like choosing bland foods and eating frequent small meals. If that’s not enough, vitamin B6 — sometimes in combination with the antihistamine doxylamine — may be recommended, the group says.
The new study — published Dec. 20 in CMAJ (Canadian Medical Association Journal) — involved 52 Canadians. Thirty were pregnant, and 22 were breastfeeding. Most identified as women, one as non-binary.
In interviews, many said they’d stopped using cannabis once they knew they were pregnant, most often because they worried about effects on the fetus. But 30 kept using, with 29 citing symptom management.
Of 33 participants who discussed breastfeeding, 28 chose to use cannabis. At that point, they often cited it as a way to relax and “wind down,” or to deal with the stress of parenting a newborn.
Chambers said research like this, looking at the motivations for cannabis use during pregnancy and breastfeeding, is helpful.
To her, the “take-home” message is that health care providers should be asking pregnant patients about whether and why they use cannabis. Ideally, she said, there should then be a “frank discussion” of the knowns and unknowns, and any alternatives for symptom management — including non-medication options.
MotherToBaby has a fact sheet on prenatal cannabis use.
SOURCES: Meredith Vanstone, PhD, associate professor, family medicine, McMaster University, Hamilton, Ontario, Canada; Christina Chambers, PhD, MPH, professor, pediatrics and family and preventive medicine, University of California, San Diego, and program director, MotherToBaby California, LaJolla, Calif.; CMAJ (Canadian Medical Association Journal), Dec. 20, 2021, online
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