West Lafayette, IN: Changes in the marijuana’s legal status under state law are not associated with increases in adverse clinical birth outcomes, according to data published in the journal Population Research and Policy Review.
Researchers affiliated with Purdue University assessed the relationship between the liberalization of state-level cannabis possession laws and two birth outcomes that are key indicators of child health: birthweight and gestational age.
Authors reported a trend toward reductions in average birthweight and gestational age for some groups of women following the relaxation of state-level marijuana penalties. However, they acknowledged that these changes were not linked to any “increases in clinically meaningful birth indicators associated with adverse child health.”
They concluded: “Our findings indicate that cannabis policy liberalization may be contributing to lower average birthweights and reduced average gestational age, but not in a manner that has increased low birthweight (<2500 g) infants or preterm (<37 weeks) births. These results indicate that while cannabis policies have not led to increases in adverse clinical birth outcomes overall, these trends are worth monitoring to ensure that increases in clinically relevant child health outcomes do not emerge as the nationwide trend toward liberalized cannabis policy persists. Additionally, while we may not be witnessing substantial changes in adverse birth outcomes, policymakers should be attentive to the opportunities to strengthen child health by considering policies that may minimize consumption, particularly heavier forms of consumption, by prospective parents.”
The findings are similar to those reported in a 2021 study which identified either “modest or no adverse effects of marijuana liberalization policies on the array of perinatal outcomes considered.”
Studies assessing the potential impacts of in utero cannabis exposure on perinatal health are inconsistent. While some observational studies have identified a link between exposure and low birth weight and/or an increased risk of preterm birth, other studies have failed to substantiate these outcomes after adjusting for confounding factors, such as tobacco smoking.
Full text of the study, “The liberalization of cannabis possession laws and birth outcomes: A state-level fixed effects analysis, 2003-2019, appears inPopulation Research and Policy Review. Additional information is available from NORML’s fact sheet, ‘Maternal Marijuana use and Childhood Outcomes.’