A study led by researchers at Oregon Health & Science University (OHSU) and the Oregon National Primate Research Center (ONPRC) reveals that using cannabis during pregnancy may negatively affect fetal lung development and future respiratory health. The findings, published in the American Journal of Physiology-Lung Cellular and Molecular Physiology, are the first to directly examine how maternal THC consumption impacts offspring respiratory health using a nonhuman primate model.
Key Findings from ONPRC Research
The research team, including Dr. Jamie Lo and colleagues at OHSU, administered daily THC edibles to pregnant nonhuman primates and compared them to a placebo group. They used fetal MRI scans to assess lung development during pregnancy and performed pulmonary function tests on the infants at six months old.
Results showed that prenatal THC exposure led to significantly decreased lung volume starting early in fetal development, a difference that persisted at six months of age. The study also found changes in lung gene expression and DNA methylation, which may help explain why the effects of THC exposure during pregnancy could last a lifetime. These changes could increase the risk of children developing chronic respiratory conditions such as asthma later in life.
Rising Cannabis Use and the Need for Evidence-Based Guidance
Cannabis use during pregnancy is becoming more common, especially in the first trimester, as some expectant mothers turn to THC products to manage symptoms like morning sickness. However, limited data on the safety of cannabis in pregnancy has left many patients and clinicians without clear guidance on the risks involved.
Dr. Lo, the study’s lead author, emphasizes the importance of these findings for healthcare providers and patients.
Dr. Eliot Spindel, senior author and professor at ONPRC, added, “Children born with decreased lung function at birth are more likely to follow a lower trajectory of lung function as they age, increasing their risk to develop childhood asthma and respiratory diseases as adults.”
What’s Next
The ONPRC team hopes their research will help inform evidence-based recommendations regarding cannabis use during pregnancy and guide clinicians in counseling their patients. While more research is needed to fully understand the long-term effects, this study raises important concerns about the potential impact of prenatal THC exposure on respiratory health.

