Tuesday, June 18, 2019

More Pregnant Women Using Cannabis, Possibly Raising Risk of Preterm Birth, Research Shows

It’s becoming more common for pregnant women in the United States to use cannabis: Between 2002 and 2017, the prevalence of past-month cannabis use increased from 3.4% to 7.0% among pregnant women overall and from 5.7% to 12.1% during the first trimester, according to a report published today in JAMA.

These and other findings, which were based on the responses of women to the National Survey on Drug Use and Health (NSDUH), highlight “the importance of screening and interventions for cannabis use among all pregnant women,” wrote Nora Volkow, M.D., director of the National Institute on Drug Abuse, and colleagues.

As part of the NSDUH, interviewers asked women about their pregnancy status; whether they used cannabis in past month; and, if so, how often they used cannabis over the past month (daily/near daily use was defined as 20 or more days of use in the past month). Beginning in 2013, respondents reporting past-year and past-month cannabis use were also asked whether any of their cannabis use was recommended by a health care professional. Those who responded no were categorized as having “nonmedical-only cannabis use.”

Volkow and colleagues analyzed data collected from 467,100 respondents overall between 2002 and 2017. During this time, the adjusted prevalence of past-month daily/near daily cannabis use increased from 0.9% to 3.4% among pregnant women overall, including from 1.8% to 5.3% during the first trimester, from 0.6% to 2.5% during the second trimester, and from 0.5% to 2.5% during the third trimester. Most women reported their cannabis use was not recommended by a health care professional: The prevalence of past-month medical cannabis use among pregnant women aged 12 to 44 years was no more than 0.68%, the authors reported.

In a separate study, also published today in JAMA, researchers reported that women who use cannabis during pregnancy may be more likely to deliver babies preterm.

Daniel J. Corsi, Ph.D., of Ottawa Hospital Research Institute and colleagues examined data collected from 661,617 women aged 15 and older who delivered a baby in an Ontario hospital between April 2012 and December 2017. Corsi and colleagues compared information on birth outcomes of 5,639 mothers who reported use of cannabis during pregnancy with 92,873 mothers who reported no use of cannabis.

After adjustment for confounding variables, Corsi and colleagues found that there was a significant association between reported cannabis use in pregnancy and preterm birth, defined by the authors as less than 37 weeks of gestation. In contrast, there was a statistically significant protective association between reported cannabis exposure and preeclampsia and gestational diabetes, the authors observed.

“These two studies send a straightforward message: cannabis use in pregnancy is likely unsafe; with an increasing prevalence of use (presumably related to growing social acceptability and legalization in many states), its potential for harm may represent a public health problem,” Michael Silverstein, M.D., M.P.H., of Boston Medical Center and colleagues wrote in an accompanying editorial.

For related information, see the Psychiatric Services article “Thinking Carefully About Marijuana Legalization: Public Health Considerations for State Policy Makers.”

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