More Pregnant Women Are Using Marijuana


As marijuana use wafts to higher levels among U.S. adults, the increase among one subset of the population – pregnant women – has some doctors worried about the health of the fetus.

Two studies appearing Dec. 19 in the Journal of the American Medical Association (JAMA) provide an updated snapshot of marijuana use around the country, with 13 percent of adults reporting that they’ve used marijuana in the past year.

But what’s leaving some medical professionals concerned is the self-reported use among pregnant women – about 4 percent of pregnant women said they have used marijuana in the past month.

While it’s a small number, it marks a 62 percent increase in use among pregnant women between 2002 and 2014, the last year of available data.

“Although the prevalence of past-month use among pregnant women (3.85 percent) is not high, the increases over time and potential adverse consequences of prenatal marijuana exposure suggest further monitoring and research are warranted,” writes the team of researchers from New York’s Columbia University.

Related: Pregnancy Bracelet Buzzes to Let Dad Know When Baby Kicks

In an accompanying editorial, three doctors from the National Institute on Drug Abuse (NIDA) take a firm stance against marijuana use among pregnant women. The risks, they say, are too great, even though the medical community has limited data on health outcomes, such as birth defects and difficulties for the child.

Although the evidence for the effects of marijuana on human prenatal development is limited at this point, research does suggest that there is cause for concern,” the researchers note.

A recent review of medical data on women who used marijuana during pregnancy shows that infants were more likely “to be anemic, have lower birth weight and require placement in neonatal intensive care than infants of mothers who did not use marijuana.”

Other studies have found links between marijuana use and subsequent difficulties with impulse control, memory and attention span in childhood, report the study authors.

Caution on Medicinal Use of Marijuana

More than half of the country allows legal marijuana use, most of them for medicinal purposes. The authors of the JAMA editorial surmise that many pregnant women may be using marijuana to overcome morning sickness and nausea that often affects them early in pregnancy.

They note that “nausea is a medically approved indication for marijuana in all states where medical use of this drug has been legalized,” but marijuana use during pregnancy shouldn’t automatically fall onto the approved list, they say in the editorial, The Risks of Marijuana Use During Pregnancy.

While both studies urge caution, the NIDA researchers expressly call for a prohibition among pregnant women. Even with the current level of uncertainty about the influence of marijuana on human neurodevelopment, physicians and other health care providers in a position to recommend medical marijuana must be mindful of the possible risks and err on the side of caution by not recommending this drug for patients who are pregnant,” they write.

Related: Marijuana Use Could Increase Alzheimer’s Risk

Of explicit concern is the infant’s neurodevelopment, or brain growth and functioning, say the NIDA researchers. “Substances that interfere with this system could affect fetal brain growth and structural and functional neurodevelopment,” they write.

In their study, the researchers from Columbia University suggest that the situation should be carefully assessed and monitored. “To ensure optimal maternal and child health, practitioners should screen and counsel pregnant women and women contemplating pregnancy about prenatal marijuana use,” they write.

The Columbia researchers also call for additional studies to explore dosage, frequency of use and clinical outcomes.