A New Study Shows THC Stays in Breast Milk for 6 Weeks

Researchers say it's "unrealistic" to tell moms to "pump and dump" breast milk to filter out THC - the chemical compound in weed - because it can linger for a month and a half.

A cohort of doctors are cautioning expectant and new moms to avoid marijuana, as the main psychoactive chemical in the drug could linger in breast milk for longer than a month.

The study, led by Childrens Hospital Colorado's Dr. Erica Wymore, tested several samples of women's breast milk for weeks after they began abstaining from weed. Researchers saw levels of tetrahydrocannabinol, the chemical that gets users high, detected in breast milk samples taken six weeks after the participating women stopped using the drug.

Of 25 women enrolled who gave birth between 2016 and 2019, just seven abstained from marijuana use for the entire duration of the study.

"I think as every new mom can attest, making major changes with using a substance that helps you cope would be really difficult in those first few weeks postpartum, when you're sleep-deprived and adjusting to motherhood," Wymore told NBCLX.

The legalization of recreational marijuana in the Centennial State got researchers thinking, and expectant moms asking questions. Wymore wanted to answer moms who were wondering: "If you do use marijuana, how long can you 'pump and dump' before your milk is safe to breastfeed?"

The study says it's "unrealistic" to tell moms to "pump and dump" until THC is undetectable, given what the results showed about the compound's length of stay.

That said, effects of THC in breast milk on infants needs to be further studied, the article in JAMA says. There was a study that followed cohorts of moms from the 1980s and on, examining marijuana use and how their children developed. The results showed "concerning outcomes with neurodevelopment and behavior" as they reached school age and beyond, Wymore added.

Wymore said she wants to encourage breastfeeding and agrees with recommendations from the American College of Obstetricians and Gynecologists and American Academy of Pediatrics that women abstain from marijuana during pregnancy and lactation.

The mothers in this recent study reported using marijuana to relieve stress and pain, or help fall asleep.

Wymore said more support is needed for mothers.

"We need to have that conversation early in pregnancy, to help women explore other symptom relief, other alternatives to help with stress, anxiety, or depression reduction, that doesn't necessarily have to be pharmacological," Wymore said. "Ways in which we can really help mothers, so we can also help them have the safest newborn breastfeeding experience as possible."