New research shows marijuana THC stays in breast milk for six weeks

By March 8, 2021 Recent News
cannabis use, pregnancy, harms

Reuters 8 March 2021
In a new study published in JAMA Pediatrics, researchers at Children’s Hospital Colorado (Children’s Colorado) have found that tetrahydrocannabinol (THC), the psychoactive component of marijuana, stays in breast milk for up to six weeks, further supporting the recommendations of the American Academy of Pediatrics, the American College of Obstetricians and Gynecologists and the Academy of Breastfeeding Medicine to abstain from marijuana use during pregnancy and while a mother is breastfeeding. This is the first study examining THC in breastmilk and plasma among women with known marijuana use in pregnancy since a 1982 study in the New England Journal of Medicine.

“With the increasing utilization of  in society as a whole, we are seeing more mothers who use marijuana during pregnancy,” said Erica Wymore, MD, MPH, primary investigator, neonatologist at Children’s Colorado and assistant professor of pediatrics at the University of Colorado School of Medicine on the Anschutz Medical Campus. “However, given the lack of scientific data regarding how long THC persists in , 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  with known prenatal marijuana use.”

The researchers studied women with prenatal marijuana use who delivered their infants at Children’s Colorado and UCHealth’s University of Colorado Hospital between November 1, 2016, and June 30, 2019. Specifically, researchers recruited women who:

  • Had a history of marijuana use during pregnancy/a positive urine test for THC when admitted for delivery
  • Were over the age of 18
  • Had an intention to breastfeed
  • Were willing to abstain from marijuana use for six weeks after delivery
  • Were willing to provide milk, blood and  during those six weeks

Of the 394 women who were screened, 25 enrolled. Seven of these women were ultimately able to abstain from  for the duration of the study. Reasons listed for the others’ inability to abstain included stress, sleep and .

The study found that, while the concentrations of THC varied from woman to woman (likely depending on their level of use, BMI and metabolism), THC was excreted in the breast milk of these seven women for up to six weeks. In fact, all of the women still had detectable levels of THC in their breastmilk at the end of the study.
READ MORE: https://medicalxpress.cohtmlm/news/2021-03-marijuana-thc-breast-weeks.