5 things to know about using marijuana while pregnant or breastfeeding

Marijuana, in any amount, isn’t safe to use during pregnancy or while breastfeeding.

But, as more and more states legalize marijuana and people tout it as a cure for morning sickness, pregnant people are left faced with sorting fact from fiction.

Lauren D. Oshman, M.D., M.P.H., is a family medicine physician and director of the Family Medicine Birth Service whose research focus includes substance use during pregnancy. 

Maria Skoczylas, M.D., is a pediatrician and medical director of the Breastfeeding and Lactation Program.

Here, Oshman and Skoczylas share five things pregnant people should know about marijuana use during pregnancy and breastfeeding.

5 reasons not to use marijuana during pregnancy or while breastfeeding

1. It can lead to problems for you and/or your baby

Smoking or vaping marijuana causes lung disease, as well as memory and mood problems, whether you’re pregnant or not.

But pregnancy is a special time when the drug can cross into the uterus, impacting the baby’s environment.

According to the American College of Obstetrics and Gynecologists, marijuana increases the risk of preterm birth, or early delivery, before 37 weeks of pregnancy.

It also increases the risk of low birth weight, where your baby doesn’t gain enough weight during pregnancy.

Marijuana is also associated with an increased risk of stillbirth, where a baby may die before or during delivery.

It’s important to know that stillbirth is still very rare and, for most people, doesn’t occur.

Marijuana use in pregnancy is also associated with long-term changes to an infant’s brain development, affecting memory, and creating learning and behavioral problems.

2. And because of that, most parents stop using cannabis during pregnancy

In Michigan, recreational marijuana has been legal for adults since 2018 and about one in three young adults between the ages of 18 to 25 report using marijuana within the last year.

However, the number during pregnancy is much smaller, with about one in six pregnant people reporting marijuana use during their pregnancy.

Your prenatal care provider will ask you questions about your use of different substances, such as marijuana, tobacco, alcohol, opioids, and more, during early pregnancy so that they can provide support and counseling to help you use less or stop during that time.

3. Chemicals from marijuana can pass through your breast milk

The main chemical in marijuana, delta-9-tetrahydrocannabinol (also known as THC), concentrates in the breast milk and can stay in the milk for as long as six weeks after use. Cannabis can also decrease the immune benefits of breast milk.

“Breastfeeding has so many benefits. We encourage people to reduce or stop using marijuana while breastfeeding,” said Skoczylas.

“We’re learning more and more about how marijuana affects your breast milk and also your baby’s development.”

4. Safe alternatives are available

Some people use marijuana in pregnancy to get high, but other people use it to treat nausea, depression or anxiety. Others use it for chronic conditions or pain they had before pregnancy.

Oshman stresses that you should feel comfortable bringing up your concerns to your prenatal care provider.

“Some people don’t want to use prescription medications for their nausea,” said Oshman.

“But we can almost always find alternative treatments so they can cut down or stop using marijuana.”

5. Legal risks do exist when you use cannabis during your pregnancy

Health care professionals are mandated reporters for newborns affected by controlled substances.

Even though recreational cannabis is legal in the state of Michigan, it’s still considered a controlled substance.

This means that if a newborn is affected by cannabis, alcohol or other controlled substances, Michigan state law requires doctors to place a report to Children’s Protective Services.

For these reasons, a CPS case manager may arrange for a home check-in on your child’s safety and your family’s well being.

“Our goal is to help keep you and your baby as healthy as possible and make sure you get the care and support you need,” said Oshman.

And patients actually appreciate the transparency and honesty about CPS reporting: recent research from Michigan Medicine found patients asked for non-punitive, respectful and early care for substance use during their pregnancy, including information on reporting to CPS.

Oshman and Skoczylas encourage patients to speak with their prenatal and newborn care providers about any substance use concerns they may have.

Visit the University of Michigan Health Partnering for the Future Clinic to get additional support on this topic and others.

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