The effects of medical marijuana laws on birth outcomes: Evidence from early adopting U.S. states

Abstract

This paper examines the effects of state-level medical marijuana laws (MMLs) in the U.S. on birth outcomes, including birth weight, length of gestation, and Apgar scores. Using individual-level natality data from the National Center for Health Statistics from 1990 to 2013, we take advantage of the geographic and temporal variation in the implementation of MMLs in a difference-in-differences estimation framework with state and year fixed effects and state-specific time trends. Overall, we find that MMLs have no impact on gestation period or Apgar scores. While MMLs lead to a statistically significant increase in birth weight by 4.4 g (0.13%), this effect is practically small. Furthermore, we find little variation in the effects of MMLs on birth outcomes across different socioeconomic subgroups and observe no lagged negative effects of MMLs on birth outcomes of children born in the MML states in the years following the legalization of medical marijuana.