Maternal Marijuana Exposure and Birth Weight: An Observational Study Surrounding Recreational Marijuana Legalization

Area of Science:

• Perinatal health
• Public health policy
• Reproductive toxicology

Background:

• Marijuana use during pregnancy is a growing public health concern.
• Understanding the impact of legalization on prenatal exposure and infant outcomes is crucial.

Purpose of the Study:

• To investigate the association between prenatal marijuana exposure and infant birth weight.
• To assess the influence of marijuana legalization and availability on these outcomes.

Main Methods:

• A retrospective cohort study of 5,343 pregnant women with urine drug screen (UDS) results.
• Data collected across three periods: before, during, and after marijuana legalization in Washington State.
• Statistical models used to analyze the relationship between marijuana exposure and infant birth weight, low birth weight (LBW), and small for gestational age (SGA).

Main Results:

• Prenatal marijuana exposure was associated with an increased risk of LBW (OR=1.42) and SGA (OR=1.51).
• The association was more pronounced for full-term infants.
• These associations persisted even after controlling for other factors and were observed across different time cohorts relative to legalization.

Conclusions:

• Marijuana exposure during pregnancy, confirmed by UDS, is linked to adverse birth outcomes like LBW and SGA.
• Despite legalization, the study found no direct impact of recreational marijuana availability on the risk of LBW or SGA in newborns.