Can You Smoke Weed While Breastfeeding? A New Study Offers Some Surprises

Breastfeeding brings numerous benefits to the baby, from immune-boosting antibodies to an overall lower risk of infant mortality. But the end of pregnancy and the postpartum period is also an incredibly difficult time, and some parents, for better or worse, turn to weed. So can you smoke weed while breastfeeding, or will it hurt the baby?

The official recommendation from the Centers for Disease Control and Prevention is that “data are insufficient to say yes or no” to smoking weed while breastfeeding. To stay on the safe side, the agency stresses that parents “should be advised not to use marijuana or products containing cannabidiol (CBD) in any form while breastfeeding.” After all, THC, the main psychoactive component of marijuana, can pass through breast milk. But a recent study shows that at least for early preterm babies, there aren’t short-term risks to drinking breast milk from a parent who smokes weed.

Researchers analyzed the medical records of more than 750 early preterm babies — babies born before 34 weeks of pregnancy, compared with a standard 38 to 42 weeks. Most of the babies were born to a mom who hadn’t recently smoked weed, but 17% of the mothers tested positive for THC. The researchers compared the health outcomes of babies who breastfed from a THC-positive parent with those who breastfed from a THC-negative parents. Overall, they found no noticeable short-term health differences between the two groups by the time they left the hospital.

“Those premature babies that got the breast milk from moms who are THC-positive, we didn’t find that they were sicker,” says study author Natalie Davis, M.D., an associate professor of pediatrics at the University of Maryland School of Medicine and neonatologist at the University of Maryland Children’s Hospital. The results have not yet been published in a peer-reviewed journal, but they were in October 2021 at an American Academy of Pediatrics conference.

Can You Smoke Weed While Breastfeeding?

Although the finding that THC-positive breast milk doesn’t hurt preemies in the short term is big, these results are limited. The researchers specifically studied early preterm babies, for whom breast milk is particularly important, Davis says. “We would try to avoid formula in these babies at all costs.” Formula is safe for babies born closer to the expected due date, she says, but it can lead to serious intestinal distress in early preterm babies.

Because the study didn’t include full-term infants and the risks and benefits of drinking THC-positive breast milk may be different in these babies, the results can’t be extrapolated to newborns in general, Davis says.

Additionally, this study only looked at short-term effects. “In this small study, we saw that the babies whose moms took THC and breastfed, they weren’t worse off medically. But that doesn’t mean that it’s safe,” Davis says. “That doesn’t mean in the long term that their development is the same. That doesn’t mean in the future they won’t have more problems.”

Lori Feldman-Winter, M.D., a pediatrician and breastfeeding expert at Cooper University Health Care in New Jersey, says these findings are reassuring, but she echoed the need to study the long-term effects of smoking weed while breastfeeding. She also emphasized the immediate and long-term “protective effects” of breastfeeding with premature babies.

“The best advice for parents is to refrain from using marijuana,” Feldman-Winter says. But not every parent will follow that advice, and doctors could be open to recommending that a THC-positive parent breastfeed their newborn, even with all the unknowns, she says. “We simply do not know the extent of harm that can be caused by transfer of THC into mother’s milk, both short and long term, and therefore cannot fully assess the risk vs. benefit ratio.”

Many of Davis’s patients are both THC-positive and breastfeeding, so she tries to walk through the risks and benefits with each family to help them decide what to do. And some will choose to breastfeed after smoking weed. “We try to really take that holistic approach in my NICU,” Davis says. “I think other NICUs, because of the risk, are scared and just say, ‘Nope, we’re not going to use this milk.’”