THC From Pot Lingers in Breast Milk for Weeks: Study

THURSDAY, March 11, 2021 (HealthDay News) -- Tetrahydrocannabinol (THC), the psychoactive ingredient in marijuana, remains in breast milk for up to six weeks and may be harmful to infants, a new study warns.

The researchers said the finding supports recommendations from the American Academy of Pediatrics and others that women shouldn't use marijuana while pregnant or breastfeeding.

"Just as we now caution mothers to avoid tobacco and alcohol in pregnancy, we recommend that all clinicians counsel women who are pregnant or considering pregnancy to abstain from marijuana throughout pregnancy and in the postpartum period," said senior investigator Dr. Maya Bunik. She is the medical director of the Child Health Clinic at the University of Colorado School of Medicine, in Aurora.

Doctors should discourage marijuana use to provide the best outcomes and allow for the safest breastfeeding, Bunik said.

Because of marijuana legalization, it is important to recognize that pregnant and breastfeeding women and their babies are a vulnerable population, and that "exercising caution is imperative," she explained.

"There is an urgent public health need for further research to quantify the long-term effects of perinatal marijuana use on infants and children, in addition to evaluating reasons for maternal use and support for mothers who struggle with abstention," Bunik said.

The study included 25 women who had used marijuana during pregnancy and gave birth between Nov. 1, 2016 and June 30, 2019. Of those, seven women stopped using pot for more than five weeks during the study period.

The women who used marijuana told researchers they did so to cope with stress, to sleep better or to relieve pain.

Most were using marijuana at least three times a week, Bunik said.

Although THC concentrations varied from woman to woman, it was excreted in their breast milk for up to six weeks after they stopped using marijuana. All had detectable levels of THC in their breast milk when the study ended.

THC in breast milk may have serious consequences for infants, Bunik said.

Research from decades ago showed significant concerns related to marijuana use during pregnancy and breastfeeding, she noted. Those concerns include effects on childhood brain development and learning issues, including attention, impulse control, and early signs of anxiety and depression.

"Today, marijuana products are five to six times more potent than when those studies were initiated, leading to the recommendations by the American Academy of Pediatrics, American College of Obstetricians and Gynecologists and the Academy of Breastfeeding Medicine to abstain from marijuana use during pregnancy and breastfeeding," Bunik said.

Dr. Roya Samuels, a pediatrician at Cohen Children's Medical Center in New Hyde Park, N.Y., said pregnant and breastfeeding women who use marijuana may need help in weaning off weed.

"Breastfeeding mothers should be wary of utilizing marijuana given that it can be passed to their infants," Samuels said, adding that its short- and long-term effects on the developing infant brain are unknown.

"It is alarming to hear of the incidence of marijuana usage in pregnant and nursing mothers," Samuels said. "Assuming this population is using the drug as a form of stress relief, perhaps more support systems should be in place to help mothers learn to use healthy coping mechanisms during this trying time."

Behavioral health professionals, obstetricians and pediatricians have key roles to play in screening women for underlying risk factors for substance abuse, such as anxiety and depression, she said.

"Appropriate identification of at-risk new mothers and effective education and support for these moms to address underlying mental health issues or elevated stress levels may help curb marijuana use in this population of patients, which in turn, would protect the vulnerable infant population as well," Samuels said.

The study was published online March 8 in JAMA Pediatrics.

More information

For more on marijuana and pregnancy, head to the U.S. Centers for Disease Control and Prevention.

SOURCES: Maya Bunik, MD, MPH, professor, pediatrics, and medical director, Child Health Clinic, Primary Care, University of Colorado School of Medicine, Aurora; Roya Samuels, MD, pediatrician, Cohen Children's Medical Center, New Hyde Park, N.Y.; JAMA Pediatrics, March 8, 2021, online