Cannabis shrinks baby lungs during pregnancy, groundbreaking primate studies show

According to groundbreaking research, prospective mothers using cannabis foods may unconsciously alter baby’s lung development, providing the clearest evidence of the lasting effects of cannabis on neonatal respiratory health to date.

The study, published this month in the American Journal of Physiological Pulmonary Cell and Molecular Physiology, uses rhesus monkeys to accurately track what happens when fetal development, a psychoactive ingredient in cannabis products.

Researchers found that infants exposed to THC before birth have significantly reduced lung capacity and function, starting to change as early as in the second trimester and persisting after birth – a warning sign that could have an impact on millions of children as marijuana use continues to rise during pregnancy.

Although babies exposed to THC look normal at birth, fine tests performed at six months old showed disturbing differences in their respiratory system. Most notably, these babies have significantly reduced functional residual capacity – the amount of air remaining in the lungs after normal exhalation – a key measure of lung function.

The researchers noted that these early changes are worrying because they may have lasting effects: “Children with reduced lung function at birth are more likely to follow a lower trajectory of lung function with age, increasing the risk of developing respiratory diseases, such as adults as chronic obstructive pulmonary disease (COPD).

In addition to measuring lung capacity, the researchers also conducted detailed molecular analysis of the baby’s lung tissue. They found changes in more than 700 genes in infants exposed to THC, many of which are related to lung development and immune function. Perhaps most worrying is the significant reduction in key growth factors required for proper lung development, including brain-derived neurotrophic factors, fibroblast growth factor basals and vascular endothelial growth factor.

Complex research methods allow scientists to overcome the limitations that plague humans’ use of marijuana during pregnancy, including self-reported bias, changes in cannabis products, and moral limitations in obtaining tissue samples.

The research team led by Dr. Lyndsey Shorey-Kendrick uses advanced MRI technology to monitor fetal lung development during pregnancy and finds lung capacity, perfusion and oxygen availability on day 110 of pregnancy (before day 110) – equivalent to the second pregnancy period of humans.

“There are several key findings highlighting the potential adverse effects of THC exposure on lung function and development in the offspring,” the researchers wrote in the paper. The results suggest that “prenatal THC exposure may have an important impact on future respiratory health and require further research in the population.”

Marijuana is already the most commonly used federal illicit drug during pregnancy, as more states legalize recreational marijuana, and more pregnancy individuals believe it is safe to control pregnancy symptoms.

The study focused specifically on edible foods (the second largest cannabis consumption form after smoking) and used doses equal to what the researchers called the “heavy human medical cannabis dose.” This allows scientists to isolate the direct effects of THC without increasing complications of smoke inhalation.

This study is particularly valuable for its use of Ganges macaques, which have similar lung development patterns as humans – with the lungs still immature at birth in mice and rats. Primate models provide a more accurate window into what can happen in human pregnancy.

Although the researchers acknowledged that the study’s sample size was small (a common limitation in primate studies), they noted that consistency in findings across multiple measures enhanced their conclusions.

“Although the results presented in this article are not definite, their potential impact on maternal THC consumption on respiratory health on offspring,” the study authors concluded.

These findings raise special concerns about the potential long-term respiratory health of children exposed to marijuana before birth. Children born with reduced lung function will usually continue to study lower trajectories of lung function throughout their lives, which may increase their vulnerability to respiratory diseases in their later lives.

As cannabis products become more effective and widely used, these results increase the urgency of evidence-based recommendations for cannabis use during pregnancy – currently, this is hampered by federal restrictions on research.

Currently, the U.S. College of Obstetricians and Gynecologists continues to advise pregnant women to avoid marijuana in all forms, and this new study seems to have great support.