Impact of THC Consumption During Pregnancy on Fetal Lung Development

Research conducted by scientists at Oregon Health & Science University (OHSU) has revealed that the use of cannabis during pregnancy, particularly its psychoactive component delta-9-tetrahydrocannabinol (THC), may adversely affect fetal lung development. This could lead to long-term respiratory health issues, such as chronic asthma, in later stages of life.

The findings, which are published in the American Journal of Physiology-Lung Cellular and Molecular Physiology, represent the first investigation into the potential respiratory health effects of maternal THC consumption on offspring. The study underscores the increasing need for informed guidelines on the safety of cannabis use in pregnant women, especially given the rising prevalence of its use to alleviate pregnancy-related symptoms like morning sickness.

Dr. Jamie Lo, who led the study, emphasized the urgency of providing evidence-based recommendations regarding cannabis use during pregnancy and breastfeeding, as many expectant mothers may be unaware of the potential risks involved.

In this study, a multidisciplinary team at OHSU assessed the effects of THC through a model involving nonhuman primates. Pregnant subjects received daily doses of THC in edible form, while a control group was provided a placebo. Researchers employed fetal magnetic resonance imaging (MRI) to monitor blood-oxygen levels in the developing lungs during critical developmental stages, including the mid-second and early third trimesters. Additionally, pulmonary function tests were conducted on the infants at six months of age.

The results indicated that maternal consumption of THC led to a significant reduction in lung volume early in fetal development, a condition that persisted into infancy. The study also observed alterations in lung gene expression and DNA methylation, processes that can influence gene activity and may have lasting implications for the child's health. These changes raise important concerns regarding the long-term respiratory health of children exposed to THC in utero.

Dr. Eliot Spindel, a senior author of the study, noted that children born with diminished lung function are at a heightened risk of experiencing lower lung function trajectories as they grow older, which could increase their susceptibility to respiratory diseases and childhood asthma. While nicotine use during pregnancy is already known to elevate asthma risk in offspring, the implications of prenatal cannabis exposure have not been thoroughly examined until now.

The research team hopes that their findings will inform healthcare providers as they counsel patients about cannabis use during pregnancy, ultimately aiming to enhance health outcomes for future generations.

For further details, refer to the study: Lyndsey E. Shorey-Kendrick et al, "Effects of maternal edible THC consumption on offspring lung growth and function in a rhesus macaque model," American Journal of Physiology-Lung Cellular and Molecular Physiology (2025). DOI: 10.1152/ajplung.00360.2024.