What every mom should know about using marijuana while breastfeeding

Caroline Praderio  

There's very limited evidence on breastfeeding and marijuana.

RAUL ARBOLEDA/AFP/Getty Images

• There's very little research on whether marijuana use while breastfeeding can impact a baby.
• Some studies suggest that THC, the main psychoactive component in marijuana, ends up in the breast milk of marijuana users.
• Until we have more data, expert organizations recommend that nursing mothers avoid the drug.

As marijuana legalization sweeps the US, research indicates that more pregnant women are using the drug. But there are still some lingering questions about its health effects for expecting moms, and experts say more research is needed on the potential risks of using pot while pregnant. Another major question that's yet to be answered by science: How a mother's marijuana use might affect their baby during breastfeeding. 

"When it comes to lactation, the vast majority of things have not been studied or studied well, and marijuana is no exception," Dr. Christina Chambers, professor in the department of pediatrics and family and preventative medicine at the University of California San Diego School of Medicine, and co-Director of the Center for Better Beginnings, told INSIDER. "We have a real paucity of data."

That lack of data is even more concerning if more mothers start using the drug while nursing. 

"With legalization, we're seeing that this is a very common exposure," Chambers added. "It's becoming increasingly common and people feel comfortable about it."

INSIDER spoke with Chambers to learn more about the existing, but very limited, science on breastfeeding and cannabis. Here's what nursing mothers should know.

Research suggests THC can end up in breast milk

THC can transfer to breast milk.

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Some studies suggest that tetrahydrocannabinol (THC), the main psychoactive component of marijuana, can cross into breast milk, Chambers explained. 

For a while, the evidence was limited to a few case reports, including one published by the New England Journal of Medicine in 1982 that looked at two mothers who smoked pot while nursing. 

THC was found in each mother's milk. But Chambers said two newer studies were published on this topic last year. 

The first looked at eight women and found THC transferred to breast milk after smoking marijuana. 

The second small study, co-authored by Chambers, analyzed milk samples from 50 breastfeeding women who said they used marijuana. Almost 90% of the women reported using the drug at least once a day, and the most common type of use was inhalation. THC was found in 34 of the 54 breast milk samples provided. 

The amount of THC detected in the breast milk was "low compared with adult doses," the authors wrote. But, as Chambers pointed out in a statement about the research, "we still don't know enough about the drug to say whether or not there is a concern for the infant at any dose, or if there is a safe dosing level."

And there's still much more to learn. 

"We know that, yes, it gets into breast milk," Chambers told INSIDER. "We don't have a really good handle on how it accumulates, and that's a big question."

There's also little evidence on how marijuana compounds in breast milk could affect a baby's health

It's not clear if marijuana exposure through breast milk can impact a baby's health.

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Chambers said two older studies (one from 1985 and one from 1990) have investigated the potential health effects for babies exposed to marijuana through breast milk. 

One study compared 55 1-year-olds who were exposed to cannabis via breastfeeding and 81 1-year-olds who weren't. They found marijuana exposure was associated with decreased motor development,

But the other (also small) study found no difference in mental or motor development between 1-year-olds who had marijuana exposure from their mother's milk and 1-year-olds who did not. 

In both of these studies, the authors couldn't entirely account for the possible impact of prenatal exposure to pot, Chambers added. 

"We really need to be doing longer-term follow-up studies, looking more comprehensively at child behavior and cognitive function following postnatal exposure through lactation, and then trying to separate that from any prenatal exposure they may have had," Chambers said.

Until there's more science, experts recommend avoiding marijuana while nursing

Groups of medical experts recommend avoiding marijuana while nursing until we know more.

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Future research may uncover risks or find that there are none. 

"It may turn out that so little gets into breast milk that it really has no impact whatsoever," Chambers said. 

But until we know more, groups of medical experts recommend that mothers who are breastfeeding steer clear of cannabis. 

In its guidance for patients, the American College of Obstetricians and Gynecologists (ACOG) recommends that breastfeeding mothers not use marijuana. In a 2018 statement, the American 

Academy of Pediatrics (AAP) also recommended nursing mothers avoid the drug, based on current evidence. The Centers for Disease Control (CDC) and Prevention says that to limit "potential risk," breastfeeding moms who use pot "should be encouraged to "abstain from or significantly reduce" their use. 

"As part of our counseling service, we say that we don't have good data to tell us whether or not there is an impact. The little bit of data that we do have suggests that at least some of the active ingredients in the drug do cross into breast milk," Chambers said. "So clearly the better-safe-than-sorry approach would be to avoid it altogether." 

Chambers also stressed the health benefits of breastfeeding and said it would be "worrisome" to pediatricians if mothers who are able and willing to nurse and counseled to stop using marijuana would instead opt to stop nursing. (Although breastfeeding isn't recommended in some situations, a wealth of scientific evidence shows that it benefits both babies and mothers.)

"[This is] a big public health question that needs to be answered," she said. 

"If you're using [marijuana] for a reason such as anxiety, the advice would be to talk to your healthcare provider about potential alternatives or ways that you can manage that until more data is available," she added.