Reported Cannabis Use in Pregnancy Dropped After New Mexico Legalization

Reported prenatal cannabis use significantly decreased from 33.8% (Epoch 1: pre-legalization) to 22.8% (Epoch 2: post-legalization). The decrease likely reflects changes in screening practices, the COVID-19 pandemic, or delayed commercialization rather than actual decreased use. Regardless of epoch, infants exposed to cannabis had smaller birth weight, length, head circumference, and lower Apgar scores.

Retrospective cohort comparing two epochs at a New Mexico hospital: pre-legalization (Jan 2019-Mar 2021, n=1,191) and post-legalization (Nov 2021-Nov 2022, n=378). Cases identified by documented self-report or positive toxicology test. Birth outcomes compared between exposed and unexposed groups.

This is one of the first studies to examine how recreational legalization actually affected reported prenatal cannabis use. The counterintuitive decrease highlights the complexity of measuring cannabis use in pregnancy and the potential impact of policy changes on screening and disclosure.

The finding that legalization did not increase reported prenatal use (and may have appeared to decrease it) does not necessarily mean actual use decreased. Changes in screening protocols, provider attitudes, and patient disclosure behavior around legalization may explain the paradox.

Single hospital. Unequal epoch sizes (1,191 vs 378). COVID-19 pandemic overlapped with both epochs. Changes in screening practices were not tracked. Cannot distinguish between actual use changes and reporting/detection changes. Short post-legalization period.