Pediatrician Esther K. Chung is a breast-feeding advocate.  The more women who do it, the better.

But she's also become concerned about the number of women who smoke marijuana while they are breast-feeding, a practice she fears might harm their infants.

Chung, a professor of pediatrics at the Sidney Kimmel Medical College of Thomas Jefferson University and the Nemours Children's Health System, frequently gives talks about the issue.

Esther K. Chung is a professor of pediatrics at the Sidney Kimmel Medical College of Thomas Jefferson University and the Nemours Children’s Health System.
Jefferson Health
Esther K. Chung is a professor of pediatrics at the Sidney Kimmel Medical College of Thomas Jefferson University and the Nemours Children’s Health System.

Her interest was sparked after she noticed that institutions weren't consistent in the advice they gave women. Some said women definitely should not smoke marijuana during the weeks or months they are breast-feeding. Others more or less left it up to the women.  The trend was similar locally, statewide, and nationally.

So Chung, who also is medical director of the newborn nursery at Jefferson, decided there was a need for more information.

"I'm not pro- or anti-marijuana," she said recently. "I'm just a pediatrician trying to keep families healthy."

Marijuana use by breast-feeding moms has probably been an issue for decades. What makes it of particular concern now? 

With growing legalization, there is growing use. It is the No. 1 illicit drug used during pregnancy.  Because of legalization, there is this increased notion that it is safe. What we want to say is that just because things are legal does not mean they are safe.

If people don't have any information about the harmful effects, then a lot of times they are going to default to thinking it's safe.  Even among health-care professionals, there is a lack of information about the harmful effects of marijuana.

We have pregnant women who say they use it because they had nausea.  It is not an acceptable medical indication at this time. But you can understand how someone who hears about it being used for nausea and vomiting in patients with cancer who are undergoing chemotherapy, and knowing in some states it's legal, how they think it might help them.

I'm worried that we may not even be aware of all the people who smoke marijuana while breast-feeding.  In our social histories, we ask if they smoke, drink alcohol or do drugs.  It's not clear to me that the average person puts marijuana in the same category as other illicit drugs.

Is medical screening that would detect marijuana use an option?

That's a controversial question — who gets screened.  What I have an issue with is whether health professionals are profiling patients.  Some medical centers have gone to universal screening of women, but that's not particularly cost-effective.  And people do worry about the negative effects. Some pregnant women are afraid to disclose that they use drugs because they are afraid social services is going to get involved in their family life. In some states, children get taken out of the custody of their parents for drug use.

On the one hand, we all want to make sure babies are going home to safe environments. On the other hand, we want to be able to help people with their addictions and not be afraid of disclosing that information, particularly if it might affect their fetus or baby.

What are the potential problems with marijuana use while breast-feeding? How could this affect an infant?

When we think about breast-feeding, we think about whether or not the drug is found in breast milk. The available data to date show that marijuana can be found at levels eight times that of the level in the mother's blood. That is really scary.  We think that's because breast milk has a high fat content, and THC — the psychoactive substance in marijuana — is concentrated in fat. When scientists look at the structure of the molecule THC, we recognize it very quickly as one that is stored in fat.

This means the baby will be receiving THC.  Most people wouldn't feed their baby marijuana, but when you think about breast milk, that is, in fact, what is happening.

Is there evidence that the drug causes harm? I think we know, even from adult studies, that marijuana impairs memory, coordination, and judgment. Recent evidence shows there are negative effects on brain development and cognitive ability. A lot of these studies have been done in older populations — adults — but more recently, teenagers. The challenge is doing studies directly with breast-feeding and babies. That's a little harder to tease out. Also, there is debate about whether occasional use poses a different threat from chronic use.

We're basically trying to piece together the limited evidence there is. But if you think about it, THC is found in large quantities in breast milk.  It is concentrated in fat.  Fat is necessary for brain development.  So if you take all the pieces of the puzzle and try to put them together, you end up with this picture that there is potential harm. And if there is potential harm, should we be exposing babies to marijuana through breast milk? Just because we don't have a huge amount of evidence doesn't make it safe.

What do the experts say?

What's very interesting is that the experts say different  things in different ways.  The American Academy of Pediatrics has definitely said that using marijuana is contraindicated while breast-feeding. Their rationale is neurodevelopmental concerns. Then we have the Academy of Breast-feeding Medicine, an organization of physicians, and they say that women should be discouraged from breast-feeding when they test positive for "drugs of abuse."   The American College of Obstetricians and Gynecologists say that women should not breast-feed if they take "street drugs" or do not control alcohol use.  But these statements are not specific. There is a whole gray zone for interpretation.

What needs to happen now?

All the maternity hospitals in the city meet through a committee called the Multi-Hospital Task Force that focuses on breast-feeding. We decided to take the fact sheet we adopted at Jefferson  and see if we could agree on a citywide one, so new parents could have the facts.  With the current situation, it's very hard for us to say, "absolutely no marijuana use." It didn't seem fair in view of what's happening with legalization, and given that a lot of expert organizations disagree. That fact sheet is being finalized now.

In the end, I think health-care professionals agree that exposing fetuses, newborns, and children to substances can be harmful. And that includes cigarettes, alcohol, and marijuana.