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Study breakdown

Cannabis-involved pregnancy hospitalizations more than doubled in Colorado after legalization

Retrospective CohortModerate evidence
The takeaway

Cannabis-involved pregnancy hospitalizations in Colorado increased from 429 to 1,210 (13.2 to 55.7 per 10,000 live births) between 2011 and 2018, with recreational dispensary access associated with the increase.

Obstetricians, policymakers, and public health officials monitoring cannabis legalization effects on maternal health.

Hospitalizations increased from 13.2 to 55.7 per 10,000 live births

What the researchers found

Cannabis-involved pregnancy hospitalizations increased more than two-fold from 2011-2018. Increasing recreational dispensaries were associated with increases in hospitalizations (IRR 1.02). Counties with no prior medical cannabis exposure had greater increases than counties already exposed.

Why it matters

The sharp increase in cannabis-involved pregnancy hospitalizations after legalization raises important public health questions about how legalization affects cannabis use during pregnancy.

The numbers in context

Hospitalizations increased from 429 to 1,210. Per 10,000 live births: 13.2 to 55.7. Mean per county: 1.7 to 4.7. Recreational dispensary association: IRR 1.02. Previously unexposed counties had greater increases.

How the study worked

Retrospective cohort study of pregnancy-related hospitalizations co-coded with cannabis diagnoses in Colorado (2011-2018). Poisson regression assessed association between county-level recreational dispensary density and hospitalization rates, controlling for baseline medical dispensary exposure.

What this study cannot tell us

Administrative data may overcount if cannabis screening became more routine. Cannot distinguish between cannabis causing the hospitalization versus incidental detection. The IRR of 1.02, while significant, is small per dispensary.

How to read the evidence

Moderate: population-level administrative data with natural experiment design, but potential confounding from increased screening.

When this study was published

Published in 2022.

The bigger picture

This is one of the first studies to directly link dispensary access to cannabis-involved pregnancy hospitalizations, providing data for the ongoing debate about legalization and maternal health.

Questions still open

  • Is the increase due to more cannabis use during pregnancy, more screening/detection, or both? Are pregnancy outcomes worse in cannabis-involved hospitalizations? Would educational interventions at dispensaries reduce use during pregnancy?

Common questions

Did cannabis use during pregnancy really increase that much?
The data show a more than two-fold increase in cannabis-involved pregnancy hospitalizations, but some of this increase could reflect more routine cannabis screening rather than more actual use.
Did counties without previous dispensaries see bigger increases?
Yes. Counties with no prior medical cannabis dispensary exposure had greater increases than counties that already had medical dispensaries, suggesting the newly available recreational market influenced use among pregnant individuals.
Does this mean cannabis harms pregnancies?
This study measured hospitalizations with a cannabis diagnosis code, not pregnancy outcomes. Whether the cannabis involvement caused harm requires separate investigation.

Read the original research

Cannabis legalization and cannabis-involved pregnancy hospitalizations in Colorado.

Preventive medicine, 156, 106993

Citation

Wang, George Sam; Buttorff, Christine; Wilks, Asa; Schwam, Daniel; Metz, Torri D; Tung, Gregory; Pacula, Rosalie Liccardo. (2022). Cannabis legalization and cannabis-involved pregnancy hospitalizations in Colorado.. Preventive medicine, 156, 106993. https://doi.org/10.1016/j.ypmed.2022.106993

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