Changes in Prenatal Cannabis Use Among Pregnant Individuals From 2012 to 2022

The prevalence of prenatal cannabis use increased from 5.5% in 2012 to 9.0% in 2022 among pregnant individuals in Northern California.

Abstract

This population-based cross-sectional study analyzed electronic health record data of pregnant individuals in an integrated health care delivery system in California to examine changes in prenatal cannabis use through self-report and urine toxicology testing during standard prenatal care between 2012 (n=33,546) and 2022 (n=43,415), and to test whether trends differed by race and ethnicity or age. The prevalence of prenatal cannabis use increased from 5.5% (95% CI, 5.3–5.8%) in 2012 to 9.0% (95% CI, 8.7–9.2%) in 2022 (adjusted prevalence ratio [aPR] 1.82, 95% CI, 1.72–1.92), with similar increases by toxicology test (aPR 1.70, 95% CI, 1.60–1.81) and self-report (aPR 2.12, 95% CI, 1.95–2.30). The increase in prevalence varied significantly across racial and ethnic and age groups, with the highest prevalence among Black individuals and those aged 13–24 across years. Although rates increased more slowly among groups with the highest prevalence of use, disparities persisted over time.

Large epidemiologic studies indicate that rates of prenatal cannabis use, daily use, and cannabis use disorder are increasing,^1–3 with a higher prevalence found among adolescents, young adults, and non-Hispanic Black individuals.^4,5 However, it is unknown whether disparities are widening over time. National data indicate significant increases in the self-reported prevalence of prenatal cannabis use from 2002 to 2019 among adults and non-Hispanic Black and non-Hispanic White individuals, but not among adolescents or those of other races and ethnicities.⁴ However, self-reported prenatal cannabis use is likely underestimated due to social desirability bias and valid concerns about legal repercussions,⁶ and studies with use verified by biological sampling are needed to better understand trends and characteristics of prenatal cannabis use.

This population-based cross-sectional study analyzed electronic health records of pregnant individuals in an integrated health care delivery system in California to examine changes in prenatal cannabis use between 2012 and 2022 by self-report and urine toxicology testing and to test whether trends differed by race and ethnicity or age.

METHODS

The sample comprised pregnant individuals in Kaiser Permanente Northern California universally screened for prenatal cannabis use by self-report and urine toxicology testing at the first prenatal visit in 2012 or 2022 (Appendices 1 and 2, available online at http://links.lww.com/AOG/D818). The study followed STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) reporting guidelines and was approved by the Kaiser Permanente Northern California IRB with a waiver of informed consent.

The crude and adjusted prevalence for prenatal cannabis use was estimated overall and by age, and race and ethnicity, which was included as a social construct due to known differences in the prevalence of prenatal cannabis use by race and ethnicity. The adjusted prevalence ratio (aPR) and 95% CI between 2012 and 2022 was estimated for prenatal cannabis use from a multivariable modified Poisson regression model with robust variance.⁷ Models were adjusted for age, race and ethnicity, Neighborhood Deprivation Index, Medicaid insurance, parity, and gestational age at screening (Appendices 3 and 4, available online at http://links.lww.com/AOG/D818) using SAS 9.4. We tested for interactions between year and age group, and year and self-reported race and ethnicity. P<.05 was considered statistically significant.

RESULTS

The sample comprised 33,546 pregnancies in 2012 and 43,415 pregnancies in 2022. In 2022 (relative to 2012), there were higher proportions of individuals aged 35 years or older (27.2% vs 20.2%) and with Medicaid insurance (11.7% vs 5.4%) and lower proportions of White individuals (31.9% vs 38.0%) (Appendix 5, available online at http://links.lww.com/AOG/D818). The prevalence of prenatal cannabis use increased from 5.5% (95% CI, 5.3–5.8%) in 2012 to 9.0% (95% CI, 8.7–9.2%) in 2022 (aPR 1.82, 95% CI, 1.72–1.92), with similar increases when use was ascertained by a urine toxicology test (aPR 1.70, 95% CI, 1.60–1.81) and self-report (aPR 2.12, 95% CI, 1.95–2.30) (Table 1).

Table 1.

Unadjusted Prevalence and Adjusted Prevalence Ratios of Cannabis Use, 2022 Compared With 2012, Overall and By Race and Ethnicity and Age Group*

The unadjusted (Table 1) and adjusted (Fig. 1) prevalence of cannabis use increased for all racial and ethnic and age groups from 2012 to 2022. The adjusted prevalence of prenatal cannabis use differed by race and ethnicity, and by age in both years, with the lowest prevalence among Asian individuals (2012: 0.7%; 2022: 2.4%) and the highest prevalence among Black individuals (2012: 20.2%; 2022: 29.3%). The adjusted prevalence of prenatal cannabis use was highest across years among those aged 13–24 (2012: 15.5%; 2022: 22.8%) and lowest among those aged 35 years or older (2012: 2.5%; 2022: 4.9%). Increases between years differed significantly across subgroups (interaction P-values for year and race and ethnicity or year and age were significant across models). Similar results were observed when self-report and urine toxicology tests were examined separately (Table 1).

Fig. 1. Adjusted prevalence of prenatal cannabis use in 2012 and 2022 by race and ethnicity (A) and by age group (B).

Young-Wolff. Changes in Cannabis Use Among Pregnant Individuals. Obstet Gynecol 2024.

DISCUSSION

Prenatal cannabis use increased between 2012 and 2022 among pregnant individuals in Northern California, during a time when cannabis was legalized for adult use (November 2016), and legal sales of adult-use cannabis began (January 2018). As reported previously, the prevalence was higher when ascertained by a toxicology test compared with by self-report,⁶ but increases were found regardless of the ascertainment method, indicating that results are not solely attributable to an increased willingness to disclose use. There were substantial differences in prenatal cannabis use by race and ethnicity and age, and significant increases in prenatal cannabis use were found among all groups over the past decade. However, lower increases in prevalence were found among pregnant individuals who already had the highest prevalence of use in 2012 (eg, those aged 13–24, Black individuals).

This study was limited to enrolled pregnant individuals with a prenatal visit in a large health care system in California, and the results may not generalize to noninsured populations or other states. Prenatal cannabis use screening occurred at entry to prenatal care, and it is unknown whether use continued throughout pregnancy.

Increases in the prevalence of prenatal cannabis use across race and ethnicity and age highlight the need to inform all pregnant individuals of the potential risks associated with prenatal cannabis use and connect them with nonjudgmental, culturally sensitive interventions, as needed. Although rates increased more slowly among groups with the highest prevalence of use, striking disparities persisted over time. Studies are needed to examine how differences in prenatal cannabis use affect cannabis-related social (eg, child protective service involvement) and health (eg, preterm birth) inequities and to test whether these disparities decline further over time.