Researchers at Oregon Health & Science University (OHSU) have uncovered evidence suggesting that cannabis consumption during pregnancy may negatively impact fetal lung development, potentially leading to chronic respiratory conditions such as asthma later in life.
The study, published today in the American Journal of Physiology-Lung Cellular and Molecular Physiology, marks the first investigation into how maternal use of THC— the primary psychoactive compound in cannabis—affects the respiratory health of offspring. It is part of a broader research initiative at OHSU aimed at understanding the long-term consequences of prenatal cannabis exposure.
The findings add to a growing body of evidence indicating that prenatal exposure to cannabis can hinder fetal development. “These findings highlight the potential risks to offspring development, adding to concerns about the safety of prenatal cannabis use,” said Dr. Jamie Lo, M.D., M.C.R., associate professor of obstetrics and gynecology at OHSU School of Medicine and senior author of the study.
Lo emphasized the urgent need for evidence-based recommendations on cannabis use during pregnancy, especially given the rising prevalence of its use, particularly in the first trimester when the fetus is most vulnerable. “There is an alarming gap in data and public awareness regarding the risks associated with cannabis use during pregnancy, which complicates the ability of healthcare providers to offer informed guidance,” she said.
Cannabis use, which has become more widespread in the United States, is commonly associated with alleviating pregnancy-related symptoms like morning sickness. However, Lo and her colleagues point to a lack of comprehensive research on the long-term effects of THC exposure during pregnancy, hindering the development of clear safety guidelines for pregnant women.
The study involved a multidisciplinary team of researchers, including Dr. Lyndsey Shorey-Kendrick, Dr. Adam Crosland, Dr. Matthias Schabel, Dr. Cindy McEvoy, and Dr. Eliot Spindel. The team conducted the study using a nonhuman primate model, administering daily THC edibles to pregnant subjects while comparing the results with a placebo group.
To assess the impact on fetal lung development, the team employed fetal magnetic resonance imaging (MRI) to measure blood-oxygen levels in the developing lungs during mid-second and early third trimesters. The researchers also conducted pulmonary function tests on the offspring at 6 months of age.
The results revealed that maternal THC consumption led to significant reductions in lung volume, a trend that began early in fetal development and persisted through the infant’s first months. Additionally, the study found alterations in lung gene expression and DNA methylation—a process that influences gene activity and may help explain the long-lasting effects of prenatal THC exposure.
While further research is needed to confirm these findings, the study’s authors expressed concern over the potential long-term implications for children’s respiratory health. Dr. Spindel, a professor in OHSU’s Division of Neuroscience and senior author of the study, warned that children born with reduced lung function are at a higher risk of developing asthma and other respiratory conditions as they grow. “We already know that nicotine use during pregnancy increases the risk of asthma in offspring,” he noted. “This study raises similar concerns about the impact of prenatal cannabis exposure, a factor that had previously been overlooked.”
The researchers hope their findings will inform healthcare providers and help improve counseling for pregnant women considering cannabis use. “Our goal is to provide better guidance for women during pregnancy to reduce health risks for both mothers and their children,” said Dr. Spindel.
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