More Women Using Marijuana While Pregnant, Study Finds

Research published in JAMA indicates that the proportion of pregnant women who have recently smoked marijuana has increased significantly from 2002 to 2014.

Surveys of US women aged 18 to 44 indicate that 3.85% of pregnant women in 2014 reported using marijuana within the last month, a 62% increase from the rate of 2.37% in 2002. There were significant disparities in marijuana use rates across different age brackets: 7.47% of pregnant women aged 18 to 25 years reported past-month marijuana use in 2014, compared to just 2.12% of pregnant women aged 26 to 44 years. However, the rate of the increase in use from 2002 to 2014 was similar for both age groups.

The reported prevalence of marijuana use within the last year grew as well, increasing to 11.63% of pregnant women aged 19 to 44 in 2014. These increases over time are similar to the trends of rising past-month and past-year use among non-pregnant women, which reached 9.27% and 15.93%, respectively, in 2014.

The study authors acknowledged that "the prevalence of past-month use among pregnant women is not high" at 3.85%, but pointed to the increases over time and the greater prevalence among younger women as causes for concern. These trends warrant additional research, and increased screening and counseling about prenatal marijuana use, they wrote.

To accompany these findings, JAMA published a viewpoint letter titled "The Risks of Marijuana Use During Pregnancy" from 3 authors affiliated with the National Institute on Drug Abuse. The letter discussed the current literature on prenatal marijuana exposure, which may be associated with lower birth weight and impaired higher-order cognitive functions during the child’s school years. It also raised concerns about the potential of the endocannabinoid system to interfere with proper development of the central nervous system.

The authors pointed to trends indicating that more women may be using marijuana to reduce nausea, particularly during the first trimester. Despite the potential medicinal uses of marijuana, this letter advises healthcare providers to “err on the side of caution by not recommending this drug for patients who are pregnant.”