THC is detectable in breast milk for up to six weeks, study finds

Photo (c) Andrii Zorii - Getty Images

Experts encourage women to avoid marijuana use during pregnancy and while breastfeeding

A new study conducted by researchers from Children’s Hospital Colorado has explored the risks associated with marijuana and breastfeeding. According to the researchers, tetrahydrocannabinol (THC), the compound in marijuana that creates the feeling of being high, can last in women’s breast milk for up to six weeks. 

“With the increasing utilization of marijuana in society as a whole, we are seeing more mothers who use marijuana during pregnancy,” said researcher Dr. Erica Wymore. “However, given the lack of scientific data regarding how long THC persists in breast milk, it was challenging to provide mothers with a definitive answer regarding the safety of using marijuana while breastfeeding and simply ‘pumping and dumping’ until THC was no longer detectable in their milk.”

“With this study, we aimed to better understand this question by determining the amount and duration of THC excretion in breast milk among women with known prenatal marijuana use,” she added.  

Abstaining from marijuana

For the study, the researchers analyzed data from women who had a history of marijuana use before pregnancy and had delivered their babies between November 2016 and June 2019 at two Colorado hospitals. Four hundred women were eligible for the study, but only 25 enrolled and just seven successfully abstained from marijuana during the first six weeks post-delivery. 

Though these women weren’t using marijuana after giving birth, they all had reported using it during pregnancy or had tested positive for the drug at the time of delivery. Ultimately, the researchers learned that all seven women had traces of THC in their breast milk six weeks after giving birth. Though the levels of THC differed in each of the women, it remained detectable nearly two months later. 

Though the study didn’t look at the effects that THC can have on infants when passed through breast milk, the researchers say several earlier studies have identified the risks associated with women smoking marijuana during pregnancy. To reduce any potential negative health effects, they urge women to abstain from marijuana both during pregnancy and during breastfeeding. 

“This study was not about the impact marijuana has on babies, but we are concerned,” said Dr. Wymore. “Especially when we consider that today’s marijuana is five to six times higher in potency than what was available prior to recent marijuana legalization in many states.” 

Take a Home Warranty Quiz. Get matched with an Authorized Partner.