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Is it safe to use cannabis during pregnancy?
Last reviewed: 02.07.2025
A study published in the Journal of Perinatology used longitudinal data from pregnant women to assess the association between prenatal cannabis use and perinatal outcomes.
In the United States, recreational cannabis use has increased following its decriminalization and legalization in many states. This has been reflected in increased use among various subgroups of the population, including pregnant women.
In a recent survey, about 22% of pregnant women did not consider weekly cannabis use to be risky. Many pregnant women find cannabis useful for reducing nausea without causing harm to the unborn child.
However, this view is not supported by the scientific literature, which reports a negative association between cannabis use and pregnancy outcomes. Cannabis use during pregnancy may result in low birth weight, which is a known predictor of infant mortality and morbidity. Prenatal cannabis use may also result in developmental delays, intrauterine growth restriction, and neurobehavioral problems.
However, there is limited research on the association between prenatal cannabis use and perinatal loss. Preliminary evidence suggests that chronic cannabis use may interfere with placental implantation and development by negatively affecting endocannabinoid processes.
Given the important role of the endocannabinoid system in fetoplacental development, this study evaluates the association between cannabis use during pregnancy and neonatal outcomes. The study also provides new data from the Stress in Pregnancy (SIP) longitudinal study.
The study included data collected between 2009 and 2017 at two prenatal obstetrics clinics in New York City. A total of 894 participants were interviewed and their medical records were reviewed. Exclusion criteria included the presence of maternal or fetal risk factors and plans to move out of the area.
Cannabis use during pregnancy was associated with a nearly twofold increase in the risk of low birth weight and a more than sixfold increase in the risk of fetal death.
The study highlights a significant association between adverse neonatal outcomes, including low birth weight and fetal death, and prenatal cannabis use. Larger studies are needed in the future to assess substance use throughout pregnancy.
The current results support an important role of the endocannabinoid system in normal gestational development.