Women Using Pot to Ease Morning Sickness in Pregnancy

Pam Harrison

August 21, 2018

Pregnant women with severe nausea and vomiting are nearly four times more likely to use marijuana during pregnancy than pregnant women who do not have nausea and vomiting, a large cohort study suggests.

Even women with mild nausea and vomiting are over two times more likely to report marijuana use during the first trimester of pregnancy, investigators report in a research letter published onlineAugust 20 in JAMA Internal Medicine.

"This is the largest study to date of nausea and vomiting in pregnancy and prenatal marijuana use," Kelly Young-Wolff, PhD, MPH, a research scientist at Kaiser Permanente Northern California in Oakland, said in a statement.

"Our findings add important evidence to a small but growing body of research suggesting that some pregnant women may use marijuana to self-medicate morning sickness," she added.

The study included 220,510 pregnant women who underwent screening between 2009 and 2016 as part of standard prenatal care. All were members of the Kaiser Permanente Northern California healthcare system.

Participants completed a substance use questionnaire and underwent a urine toxicology test during the first trimester of pregnancy at approximately 8 weeks' gestation.

"All positive toxicologic test findings were confirmed with a laboratory test result," investigators note.

The majority of pregnant women were between 25 to 34 years of age and 8.3% reported using marijuana in the year prior to becoming pregnant.

Investigators found that 2.3% of the study sample had severe nausea and vomiting in pregnancy (NVP) and 15.3% had mild NVP.

"The prevalence of prenatal marijuana use by self-report or toxicologic test findings was 5.3%," study authors note.

However, the rate was significantly higher among women who had severe NVP, at 11.3%, compared with 4.5% of those who did not experience NVP (adjusted odds ratio [aOR], 3.80; P < .001). Among those with mild NVP, 8.4% reported prenatal marijuana use (aOR, 2.37; P < .001).

"We hope our study can help alert clinicians to the fact that women with nausea and vomiting in pregnancy are more likely to use marijuana," Nancy Goler, MD, associate executive director for the Permanente Medical Group, Vallejo, California, said in a statement.

"Pregnant women need to be screened and given the information about the possible negative effects [of marijuana use] while also receiving medically recommended treatment options," she added.

As investigators note, the health effects of prenatal marijuana are unclear. National guidelines recommend that women discontinue using marijuana on becoming pregnant because of concerns about its potential effect on fetal neurodevelopment, its potential to lead to low birth weight, and possible adverse effects of marijuana smoke on the developing fetus.

The authors have reported no relevant financial relationships.

JAMA Inter Med. Published online August 20, 2018. Research letter

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