Pregnant Women in Legal Cannabis States Are Less Likely to Complete Treatment | Research

The takeaway

Among 13,088 pregnant women admitted for cannabis use treatment, those in states with full legalization had 67% lower odds of completing treatment compared to states where cannabis was illegal.

Obstetricians, addiction medicine specialists, policymakers weighing legalization effects, and prenatal care providers.

What the researchers found

This is the first large-scale study to examine whether cannabis legalization affects treatment completion among pregnant women—a uniquely vulnerable population where treatment success has direct consequences for two patients.

Using the Treatment Episode Data Set-Discharge (national treatment data from 2020–2022), the researchers analyzed 13,088 pregnant women admitted for cannabis use across states with different legal frameworks: fully legalized, medical only, or illegal.

The finding was stark: pregnant women in states with full legalization had an adjusted odds ratio of 0.33 for treatment completion compared to illegal states—meaning 67% lower odds of completing treatment. The comparison with medical-only states also showed lower completion, but the effect was strongest in full legalization states.

This doesn't necessarily mean legalization causes treatment failure. In legal states, cannabis is normalized, making motivation to quit less compelling. Referral pathways may differ—in illegal states, more women may be mandated to treatment (and mandated patients may have higher completion rates due to legal consequences). The types of treatment available and the severity of cannabis use may also differ by legal context.

The overall completion rate was only 28.3% across all states—treatment for cannabis use during pregnancy has very high dropout regardless of legal status.

Why it matters

Cannabis use during pregnancy is the most commonly used illicit substance in pregnancy (RTHC-00209), and the evidence for fetal harm is growing. If legalization reduces treatment completion among pregnant users, that's a public health consequence that legalization advocates and regulators need to address—perhaps through pregnancy-specific outreach, incentive programs, or alternative intervention models.

The numbers in context

N = 13,088 pregnant women. 28.3% completed treatment overall. Full legalization: AOR 0.33 (67% lower completion odds) vs. illegal states. Treatment data from 2020–2022 across varying legal frameworks.

How the study worked

Retrospective cross-sectional analysis of the Treatment Episode Data Set-Discharge (TEDS-D), 2020–2022. N = 13,088 pregnant women aged 12+ admitted for cannabis use. States categorized by legalization status (fully legal, medical only, illegal). Multivariable logistic regression for treatment completion. Subgroup analyses by treatment setting and referral source.

Who was studied

N=13,088 pregnant women aged 12 or older admitted for cannabis use in the US from 2020 to 2022.

What this study cannot tell us

TEDS-D captures treatment facility data, not all cannabis users—many pregnant users never enter treatment. The definition of 'treatment completion' varies by setting and program. Confounders at the state level (treatment availability, cultural attitudes, referral mandates) may explain the association more than legalization itself. Cross-sectional by state design can't control for all between-state differences. The 2020–2022 period overlaps with COVID, which disrupted treatment services differently by state.

How to read the evidence

Large national dataset with multivariable adjustment—strong for identifying the association but can't prove legalization caused lower completion.

When this study was published

Published in 2026 with 2020–2022 treatment data, capturing the current legalization landscape.

The bigger picture

This adds a concerning dimension to the legalization evidence. RTHC-00181 found mostly neutral mental health effects from legalization at the population level, and RTHC-00175 mapped monitoring recommendations. But this study identifies a specific subgroup—pregnant women needing cannabis treatment—where legalization may be actively harmful by reducing treatment engagement. It connects to the prenatal evidence cluster (RTHC-00209, 00191, 00217, 00216, 00226) by showing that legalization may increase the exposed population.

Replication

Not stated in abstract.

Funding

Not reported in abstract.

Conflicts of interest

Not reported in abstract.

Questions still open

Is the lower completion driven by reduced motivation in legal states or by different referral patterns (fewer mandatory referrals)? Would pregnancy-specific cannabis interventions improve completion rates in legal states? Does lower treatment completion translate to worse neonatal outcomes?

Read the original research

Is cannabis legalization associated with treatment completion? A study of pregnant women admitted for cannabis use in substance use treatment facilities, 2020-2022.

Drug and alcohol dependence, 279, 113023

Drug and Alcohol Dependence is a well-respected journal focusing on substance use research.

View on PubMed ↗Publisher’s paper ↗

Citation

Carandang, Rogie Royce; Rhee, Taeho Greg; Ha, Toan; Cunningham, Shayna D. (2026). Is cannabis legalization associated with treatment completion? A study of pregnant women admitted for cannabis use in substance use treatment facilities, 2020-2022.. Drug and alcohol dependence, 279, 113023. https://doi.org/10.1016/j.drugalcdep.2026.113023