Should Moms Who Smoke Weed Continue to Breast-feed?

Dr. Torri Metz,​ an obstetrician specializing in high-risk pregnancies at the University of Colorado Hospital and Denver Health Medical Center, says that increasingly, patients are disclosing a potentially concerning habit: They’re using marijuana ​while pregnant and breast-feeding.

Colorado is one of four states plus the District Columbia that have legalized marijuana for recreational use, with nearly half of states in the U.S. having now legalized the drug to some extent, frequently for medical use. Metz says it’s unknown whether actual use among expectant and breast-feeding moms has increased, or if more patients just feel at ease disclosing it, given the changing legal landscape​.

But a recent survey published in Nursing for Women's Health ​– the clinical practice journal of the Association of Women's Health, Obstetric and Neonatal Nurses ​​​​​– found that marijuana use during pregnancy is on the rise, with approximately 10 percent of pregnant women in the U.S. saying they used the drug while pregnant – despite associated risks ranging from lower birth weight and an increase in pre-term labor to issues with fetal development that could affect attention, memory and problem solving, according to the authors.

In addition, more practitioners​ – from doctors and nurses to lactation consultants – are fielding patients' questions on the topic. Their message? Pregnant women should quit using marijuana immediately, whether smoking it, consuming it, applying the drug topically or otherwise. “We always counsel people to stop,” says Metz.

Where it gets more complicated, however, is that with scant research on the impact of marijuana on a nursing baby, experts vary on whether a mom should stop breast-feeding – which has been proven highly beneficial to babies' physical and mental health – if she’s unable to quit smoking weed, or using cannabis in any other form.​ ​

“I think clinicians are extremely frustrated,” Metz says, by a lack of data guiding them on the topic. “Caregivers are trying to weigh the known benefits of breast-feeding against the possibility of marijuana exposure and then that’s where you start to see difference in opinion – because it is just that.”

Research published in September in the journal Breastfeeding Medicine found that 41 percent of lactation professionals surveyed from the New England area while attending a professional conference in Vermont reported recommending that moms continue breast-feeding, even if unable to quit using marijuana, because of the benefits of breast-feeding.

Another 45 percent said their advice varied based on certain factors, including how heavily a mom used the drug. Only 15 percent said they’d recommend the mother stop breast-feeding if she couldn’t quit using marijuana.​

“We recognize that Vermont probably has a somewhat more permissive attitude about marijuana, [which] presumably filters down to some of these lactation professionals and their practices,” says Sarah H. Heil,​ the study’s senior author and an associate professor of psychiatry and psychological sciences at the University of Vermont. ​Lactation professionals surveyed estimated that 15 percent of their clients during the past year who breast-fed also smoked marijuana.

But while Heil expects recommendations might be more conservative on breast-feeding and marijuana use in more conservative parts of the country, she believes the differing opinions captured by the research would be evident  elsewhere. “I suspect there probably would still be a fair amount of conflict in the recommendations that are being made in different parts of the country,” Heil says.

During the past 10 years, research finds that U.S. marijuana use has more than doubled, with about 9.5 percent of the population​ saying they've used it in the past year. However, the prevalence of pot abuse among those who say they’ve used pot dropped to less than one-third. Similarly, attitudes toward it have also softened, with a recent Gallup poll finding that well over half of Americans support the legalization of marijuana.

But significant concerns remain about the the drug's impact on the brain, from its​ ability to undermine basic motor functioning to disrupting emotions or behavior, particularly in heavy or longtime users. And some experts worry about the potential short- and long-term impact on babies whose mothers used marijuana while breast-feeding them.

“I’ve become more concerned because we keep getting lots and lots of phone calls about marijuana use, not so much by [breast-feeding] women but other health care authorities, because they don’t know quite know how to respond to the issue,” says Thomas Hale,​ a pharmacologist, professor of pediatrics and director of the InfantRisk Center at Texas Tech University School of Medicine in Amarillo.

Hale authored Medications and Mothers’ Milk​,​ a reference book now in its 16th edition and a veritable bible on recommendations regarding breast-feeding and drug use – from prescription meds to illicit street drugs – that's referred to widely by lactation professionals.

Hale plans to research the issue further. But despite a lack of conclusive evidence, his advice to breast-feeding moms is simple: “They should not continue breast-feeding if they’re going to continue using marijuana," he says. " The detrimental effects could be real and could be recognized later on and it could produce long-term damage in the baby.”

For starters, he says it’s known that some of the intoxicating chemical in marijuana – or delta-9-tetrahydrocannabinol, also called THC – passes through the mother’s breast milk to the nursing baby. However, because much of what's understood about this comes from a decades-old case involving one mother and child, experts say determining how much a nursing baby gets from the marijuana produced today will require further study.

“We know there are some brain deficits that can occur from chronic exposure to marijuana. Now we don’t know if those levels in [breast] milk ... are high enough to produce these,” he says.

Still, the latest edition of Medications and Mothers’ Milk gives marijuana its highest hazard rating, noting concerns ranging from a sedating effect on mom and baby to poor feeding patterns and possible decreased milk production. Hale reports that both human and animal studies suggest early exposure to marijuana may produce long-term changes in a child's behavior and mental health.