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NIDA. (2016, June 20). Pregnancy and Drugs: Update (Part 2 – Marijuana, Opioids, and Illegal Drugs). Retrieved from

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The NIDA Blog Team
June 20 2016
Image of a pregnant belly

This is the second part of an update to the post, “Using Drugs When Pregnant Harms the Baby.”

Last week we described some of the recent scientific research about the dangers to an unborn baby’s health if the baby’s mother smokes or vapes while she’s pregnant. Now let’s look at recent discoveries about how a pregnant woman’s use of marijuana, opioids, or other drugs can affect her baby.

Weed and pregnancy don’t mix

You’ve probably heard that marijuana can affect a teen’s brain, which is still developing. Well, think of how it might affect a tiny baby’s brain. The active ingredient in marijuana, THC, may affect the way a baby’s brain grows and develops. A recent study found that if a pregnant mouse is exposed to marijuana, the baby mice have difficulty with solving problems, paying attention, remembering information, and socializing. The reasons aren’t clear yet, but it’s possible that THC is affecting the development of the brain cells (or neurons) that are important to those skills and behaviors.

Another study found that pregnant women who smoke marijuana may triple their risk for a stillbirth (a baby who dies after 20 weeks or more in the womb).

Research also discovered that using marijuana in pregnancy is associated with a 77 percent higher risk for having a baby with a low birth weight—which sometimes results in health problems such as sickness early in life or long-term learning disabilities—and can double the risk of a baby being placed in intensive care.

These studies didn’t show that using marijuana while pregnant directly caused stillbirths and low birth weight; more research is needed to see exactly what’s behind the connection. For now, it’s important for expectant mothers to know about the significantly higher health risks associated with marijuana use.

Pain reliever misuse = pregnancy problems

The dramatic increase in the misuse of prescription opioid pain relievers in the last several years has brought new attention to the dangers of using them while pregnant. Researchers have found that a pregnant woman’s use of opioids can lead to neonatal abstinence syndrome (NAS), where the baby becomes dependent on the drug just as the mother does. It can also bring a higher risk for the baby to have heart defects, spine problems, and buildup of fluid in the brain (hydrocephalus).

Other drugs: not for babies, either

An expecting mother’s use of other kinds of drugs has all kinds of risks for the baby.

For instance, using cocaine can lead to premature birth, low birth weight, and NAS. A pregnant woman who uses heroin has an increased risk of miscarrying, having a baby of low birth weight, and NAS.

And let’s not forget alcohol, which can cause brain damage in an unborn child, leading to problems with development, thinking ability, and behavior.

If you’re pregnant and you smoke, drink alcohol, or use drugs, you can get help—and help your baby in the process. Your doctor can recommend programs to help you quit, or you can call 1-800-662-HELP (4357), the Helpline of the Substance Abuse and Mental Health Services Administration (SAMHSA); visit SAMHSA’s online treatment locators; or use SAMHSA’s Step-by-Step Guides.

Update: For the latest on marijuana use and pregnancy, read this blog post.