Daily Cannabis Use Before and During Pregnancy Rising in Northern California

By Marilynn Larkin

July 24, 2019

NEW YORK (Reuters Health) - Self-reported cannabis use before and during pregnancy has been rising in Northern California, with daily use increasing most rapidly, researchers say.

"Our prior research found that pregnant women are more likely to screen positive for cannabis use via urine toxicology testing versus self-report, strongly indicating that cannabis use during pregnancy is underestimated via self-report," Dr. Kelly Young-Wolff of Kaiser Permanente Northern California in Oakland told Reuters Health by email.

"In addition," she said, "women who disclose cannabis use may underreport the frequency with which they use, and the true prevalence and frequency of cannabis use before and during pregnancy may be higher than what we report in this study."

Dr. Young-Wolff and colleagues studied data from 367,403 pregnancies among 276,991 women who completed a self-administered questionnaire on cannabis use during prenatal care from 2009 through 2017.

As reported online July 19 in JAMA Network Open, 35.9% of women were Caucasian; 28%, Hispanic; 16.6%, Asian; 6%, African American; and 13.5%, other.

Among participants, 1.2% were ages 11 to 17; 15.3%, 18 to 24; 61.4%, 25 to 34; and 22%, over 34. The median neighborhood household income was $70,472.

The adjusted prevalence of cannabis use in the year before pregnancy increased from 6.8% to 12.5% during the study period, and the adjusted prevalence of cannabis use during pregnancy increased from 1.95% to 3.38%.

Annual relative rates of change in self-reported daily cannabis use (1.115), weekly use (1.083), and monthly or less use (1.050) in the year before pregnancy increased significantly, with daily use increasing most rapidly (from 1.17% to 3.05%).

Similar findings were seen for self-reported use during pregnancy: annual relative rates of change in daily use (1.110), weekly use (1.075) and monthly or less use (1.044) increased significantly from 2009 to 2017, with daily use increasing most rapidly (from 0.28% to 0.69%).

By 2017, the authors note, self-reported daily use reached 25% among those who used during the year before pregnancy and 21% among those who used during pregnancy.

"The prevalence of cannabis use via urine toxicology testing has also increased significantly over time," the authors stated, "suggesting that results are not simply due to greater willingness to self-report prenatal cannabis use in recent years."

Dr. Young-Wolff said, "National guidelines indicate that there are no approved indications for prenatal cannabis use and strongly recommend that clinicians screen for and advise against cannabis use during pregnancy due to concerns about low birthweight and impaired neurodevelopment."

"In our study, 96% of women who self-reported cannabis use during pregnancy also reported use in the year prior to pregnancy," she noted. "This suggests that there is a great opportunity for clinicians to reduce possible harms by providing education about the potential health effects of prenatal cannabis use to all women of reproductive age, and particularly to those who are trying to get pregnant."

Young-Wolff's team recently received a five-year grant from the US National Institute on Drug Abuse to investigate whether prenatal cannabis use is associated with increased risk of maternal, fetal, and neonatal outcomes using data from urine toxicology testing, self-reported frequency of prenatal cannabis use, and mode of cannabis administration.

"In addition," she said, "we will test whether legalization of cannabis for recreational use in California in 2018 and local regulatory practices, such as retailer bans, are associated with variation in prenatal cannabis use."

Dr. Torri Metz of University of Utah Health in Salt Lake City, coauthor of a related editorial, commented by email that the findings are "concerning, as marijuana use, and especially frequent marijuana use, has been associated with adverse pregnancy outcomes including poor fetal growth and abnormal neurodevelopment."

Further, she said, "this study was performed in California over a time period when marijuana was not yet legalized. It is possible that the rates of use are higher in states with legalization."

"At this time, clinicians need to ask pregnant women about marijuana use," she noted. "Pregnant women should be advised not to use marijuana during pregnancy. It is important for clinicians to query about the reason for use, as many women perceive a benefit of marijuana use for the treatment of conditions such as nausea of pregnancy, depression, or anxiety."

"In many cases," she concluded, "safer and more efficacious treatment options can be offered."

SOURCE: http://bit.ly/2Y0qyrH and http://bit.ly/2Y0SNq8

JAMA Netw Open 2019.