Marijuana Use in Pregnant Teens 'Worryingly' High

Megan Brooks

April 20, 2017

New data show high rates of marijuana use among pregnant teenagers in the United States, especially in the first trimester.

"Our study adds important new details to the existing literature. We found that almost 4% of pregnant women reported marijuana use in the past month. This rate is a little over half the rate we found among their nonpregnant counterparts, but still much higher than the 0% we would like to see," lead investigator Nora Volkow, MD, director of the National Institute on Drug Abuse, told Medscape Medical News.

"However, and worryingly, we were surprised" to find a higher rate of marijuana use among pregnant than among nonpregnant teens, she said.

The study was published online April 17 in the Annals of Internal Medicine.

Most Commonly Used Illicit Drug

Marijuana is the illicit drug most commonly used during pregnancy. Because of concerns over potential harmful effects on the developing fetus, the American College of Obstetricians and Gynecologists (ACOG) recommends that pregnant women not use marijuana.

Using data from the National Survey on Drug Use and Health for 2002 to 2015, Dr Volkow and colleagues examined the prevalence of past-month marijuana use among females aged 12 to 44 years.

Among 14,400 pregnant and 395,600 nonpregnant respondents, self-reported marijuana use was less common among pregnant women than among nonpregnant women (3.82% vs 7.54%), except among pregnant teenagers. Marijuana use was more than twofold higher among pregnant teenagers aged 12 to 17 (14%) than among their nonpregnant peers (6.4%).

Marijuana use was particularly common in the first trimester (6.44%) but was also prevalent in the second (3.34%) and third trimesters (1.82%).

"The higher prevalence of marijuana use observed in the first trimester as opposed to later in the pregnancy suggests that some women are likely to resort to marijuana for managing their nausea," said Dr Volkow.

In both pregnant and nonpregnant groups, self-reported marijuana use was lower among women aged 26 years or older. Among pregnant females, prevalence of marijuana use was higher among blacks than among other racial/ethnic groups.

"These results matter," said Dr Volkow, "because, compared with pregnant adults, pregnant teens are at increased risk for having pregnancy-related complications, premature delivery, and delivering babies with developmental problems. Babies born to mothers using marijuana during pregnancy, and particularly during its early stages, can suffer long-term effects of maternal prenatal drug use."

It is important to consider these findings in a broader context in which young people increasingly view marijuana "not just as a benign, but even as a beneficial drug," Dr Volkow said.

Toxic Consequences

"The impact of policy liberalization and reduced perception of harm on public health may be even more profound, given the steady increases in marijuana's potency in recent years. All these factors combined may turn out to be unpredictably and particularly toxic vis-à-vis the potential long-term adverse effects of marijuana exposure during fetal development," she added.

For healthcare providers, "The key is education and keeping the channels of communications always open. We have a responsibility to teach more and preach less. So, becoming acquainted with what science knows about an issue and offering it in a balanced, neutral way is absolutely essential," she noted.

In the case of marijuana use among pregnant women, young women should be aware of several facts, Dr Volkow said.

"THC and other cannabinoids in marijuana interact with the body's natural cannabinoid system, which plays a role in fetal development. These cannabinoids also play a role in brain maturation, influencing the movement of neurons to their final destinations and ensuring proper connections between cells.

"Studies in animal models have found that even low doses of prenatal THC can cause cognitive dysfunction and emotional dysregulation, as well as increased vulnerability to addiction in adulthood," said Dr Volkow.

The National Academy of Medicine has concluded that there is strong evidence that marijuana use during pregnancy is linked to lower birth weight.

"This is why women who become pregnant should refrain from using marijuana," Dr Volkow said.

No Safe Level of Use

Nathaniel DeNicola, MD, FACOG, an obstetrician-gynecologist at George Washington University, in Washington, DC, agrees.

"My counseling is most specific to pregnancy: there is no safe time, type, or amount of marijuana in pregnancy," he told Medscape Medical News. "That is, we don't have data to say that different types are safe (edible, vaporizers, etc), we can't say that 'just a little' is okay, and there is no safe point in pregnancy when marijuana use can be considered safe ― particularly in the first trimester, when nausea and vomiting are the most severe.

"For pregnancy, it's important to remember that marijuana does increase your risk for a small/growth-restricted baby and preterm baby," said Dr DeNicola, who was not involved in the study.

The role of healthcare providers is to be a "trusted source for discussing any questions they may have about pregnancy, but also being an important guide about the information we have about marijuana use, which all pushes toward precautionary principles and counseling against its use during pregnancy," said Dr DeNicola.

The study had no commercial funding. The authors have disclosed no relevant financial relationships.

Ann Intern Med. Published online April 18, 2017. Abstract


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as: