Oregon Health & Science University researchers have found that consuming cannabis while pregnant could affect fetal lung development and function, potentially leading to the development of chronic respiratory health conditions, such as asthma, in adolescence and adulthood.
The study, published today in the journal American Journal of Physiology-Lung Cellular and Molecular Physiology, is part of ongoing research by OHSU scientists to understand the potential long-term impacts of prenatal cannabis exposure. It is the first study to examine the effects of maternal THC consumption on their offspring's respiratory health.
"These findings add to the growing evidence that prenatal cannabis exposure may adversely affect offspring development," said the study's corresponding author, Jamie Lo, M.D., M.C.R., associate professor of obstetrics and gynecology (maternal-fetal medicine) in the OHSU School of Medicine and the Division of Reproductive and Developmental Sciences at the Oregon National Primate Research Center at OHSU.
"As the prevalence of prenatal cannabis use is rising, there is an urgent need for evidence-driven recommendations on the safety of use during pregnancy and while breastfeeding."
Delta-9-tetrahydrocannabinol, or THC, is the main psychoactive ingredient in cannabis, a substance growing in popularity and availability in the United States. Cannabis use in pregnancy is prevalent, especially during the first trimester — a time when the fetus is most vulnerable to environmental exposures — to mitigate common symptoms like morning sickness, Lo says.
However, she says, the limited available evidence-based data on its use during pregnancy has led to a lack of awareness among the public regarding potential risks and hinders clinicians from counseling patients effectively on possible adverse effects.
The research involved a multidisciplinary team, including Lo and OHSU colleagues Lyndsey Shorey-Kendrick, Ph.D., Adam Crosland, M.D., M.P.H., Matthias Schabel, Ph.D., Cindy McEvoy, M.D., and senior author Eliot Spindel, M.D., Ph.D.
In a model using nonhuman primates, researchers administered THC in a daily edible and compared its effects with a group receiving a placebo. Researchers first measured blood-oxygen levels in developing lungs using fetal magnetic resonance imaging, or MRI, at mid-second trimester and early third trimester, followed by pulmonary function testing of infants at 6 months old.
Maternal THC edible consumption resulted in significantly decreased lung volume, beginning early during fetal development and still present at 6 months old. The results also showed that prenatal exposure to THC altered lung gene expression and DNA methylation — a process that helps determine whether the gene is active and affects the child's health — which researchers say may explain why exposure during pregnancy can last a lifetime.
While more research is needed to understand these effects definitively, researchers say these results raise clear concerns for potential effects of maternal THC edible consumption on offspring respiratory health.
"This is certainly something that raises alarm bells, because 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," said Spindel, professor in the Division of Neuroscience at ONPRC. "We know nicotine use in pregnancy can increase the risk of asthma in offspring, but no one has thought that about prenatal cannabis exposure until now.
"Our hope is that data from this study will help guide providers when counseling patients on cannabis use in pregnancy, so we can ultimately improve health outcomes for all children."
Research reported in this publication was supported by the Office of the Director, National Institutes of Health, the Eunice Kennedy Shriver National Institute of Child Health & Human Development, and the National Institute of Drug Abuse, of the National Institutes of Health, under Award Numbers P51OD011092, K12HD085809, K12HD000849, R03HD097116, and DP1DA056493. Research was also supported by NIDA Drug Supply Program, and Silver Family Innovation. The contents of this study are solely the responsibility of the authors and do not necessarily represent the official view of the sponsors.
All research involving animal subjects at OHSU must be reviewed and approved by the university's Institutional Animal Care and Use Committee (IACUC). The IACUC's priority is to ensure the health and safety of animal research subjects. The IACUC also reviews procedures to ensure the health and safety of the people who work with the animals. The IACUC conducts a rigorous review of all animal research proposals to ensure they demonstrate scientific value and justify the use of live animals.
