RESEARCH LETTER

Self-reported Medical and Non-medical Cannabis Use Among Pregnant Women in the United States

Methods : Data were from women aged 12 to 44 years who participated in the 2002-2017 NSDUH, a representative survey of the US civilian, noninstitutionalized population.2 Collection of NSDUH data was approved by the institutional review board at RTI International.2 Data were collected by interviewers during personal visits. Oral informed consent was received from respondents. The annual mean weighted response rate of the 2002-2017 NSDUH was 63.6%. Although methods to assess nonresponse bias vary, NSDUH trends have been comparable with trends from other population surveys.

The NSDUH collected sociodemographic characteristics, current pregnancy status, past-month cannabis use, pastmonth number of days of use, and daily/near daily use (≥20 days in the pastmonth). Respondents who answered “yes” to “Are you currently pregnant?” were asked “How many months pregnant are you?”

Starting in 2013, respondents reporting past-year and past-month cannabis use were asked if any cannabis use was recommended by health care professionals. If answering “no,” respondents were classified as having past-month “nonmedical-only cannabis use.” If answering “yes,” they were asked if all cannabis use was recommended, and if answering “yes” to that question, they were classified as having past-month “medical-only cannabis use.”

Using logisticandlinear regressions,we examined changes in adjusted (controlling for age, race/ethnicity, and family income) past-month cannabis use and use frequency and prevalence of past-month medical-only and non medical-only cannabis use by pregnancy status. Statistical significance was set at P < .05 by 2-sided t test. Analyses used SUDAAN software, release 11.0.1 (RTI International), to account for the NSDUH’s complex design and sampling weights.

Results : Based on 467 100 respondents overall between 2002 and 2017, prevalence of past-month cannabis use, daily/near daily cannabis use, and number of days of cannabis use all increased among pregnant (and nonpregnant) women aged 12 to 44 years from 2002 to 2017 and was higher for the first trimester than for the second and third trimesters. Between 2002-2003 and 2016-2017, adjusted prevalence of pastmonth cannabis use (Figure, A) increased from 3.4% to 7.0% among pregnant women overall (difference, 3.6%; 95% CI, 1.92%-5.29%) and from 5.7% to 12.1% during the first trimester (difference, 6.4%; 95% CI, 2.56%-10.29%). Adjusted prevalence of past-month daily/near daily cannabis use (Figure, B) increased from 0.9% to 3.4% among pregnant women overall (difference, 2.5%; 95% CI, 1.40%-3.59%), from 1.8% to 5.3% during the first trimester (difference, 3.5%; 95% CI, 1.08%-5.98%), from 0.6% to 2.5% during the second trimester (difference, 1.9%; 95% CI, 0.42%-3.44%), and from 0.5% to 2.5% during the third trimester (difference, 2.0%; 95% CI, 0.25%-3.66%). Adjusted past-month mean number of days of cannabis use (Figure, C) increased from 0.4 to 1.1 days among pregnant women overall (difference, 0.7; 95% CI, 0.38-0.99), from 0.8 to 2.0 days during the first trimester (difference, 1.2; 95% CI, 0.46-1.92), from 0.2 to 0.7 days during the second trimester (difference, 0.5; 95% CI, 0.08-0.81), and from 0.3 to 0.7 days during the third trimester (difference, 0.4; 95% CI, −0.06 to 0.92).

Among pregnant women between 2013 and 2017, past month cannabis use was 0.5% for medical-only purposes (Table). Medical-only cannabis use did not differ by pregnancy status, but nonmedical-only cannabis use was higher among nonpregnant women (8.7%) than pregnant women (4.0%) (difference, 4.7%; 95% CI, 4.01%-5.38%).

Discussion : Prevalence and frequency of past-month cannabis use among pregnant women increased between 2002 and 2017 and were higher for the first trimester than later trimesters. Past-month clinician-recommended cannabis use was low among pregnant women, and nonmedical use was lower than among nonpregnant women. Although many states have approved cannabis for nausea/vomiting (including in pregnancy),3 the results suggest that clinicians might not recommend it during pregnancy, perhaps reflecting the American College of Obstetricians and Gynecologists recommendation that pregnant women discontinue cannabis consumption.4 Study limitations include likely underestimated cannabis use during pregnancy (eg, while unaware of being pregnant).5 Also, the NSDUH is subject to recall bias.

Cannabis effects on fetal growth (eg, low birth weight and length) may be more pronounced in women who consume marijuana frequently, especially in the first and second trimesters.4 This study highlights the importance of screening and interventions for cannabis use among all pregnant women.

Nora D. Volkow, MD
Beth Han, MD, PhD, MPH
Wilson M. Compton, MD, MPE
Elinore F.McCance-Katz, MD, PhD