A joint study from Western and Queen’s universities finds that daily use of cannabis during pregnancy can lead to reductions in birth weight along with decreased brain and liver growth in newborns.
The research, published in the journal Scientific Reports, used a rat model and human placental cells to study the effects of THC, the main psychoactive ingredient in cannabis, on pregnant women.
Researchers found that a rat model regularly exposed to a low dose of THC during pregnancy — a dosage that’s intended to mimic the daily use of cannabis — resulted in an eight per cent reduction in birth weight, along with a more than 20 per cent decrease in brain and liver growth.
Co-author Dr. Dan Hardy said the research backs previous studies that have linked cannabis use during pregnancy to low birth weight in newborns.
“Clinical data is complicated because it is confounded by other factors such as socioeconomic status,” said Hardy.
“This is the first study to definitively support the fact that THC alone has a direct impact on placental and fetal growth.”
Researchers say the growth reductions observed in babies are likely due to how THC was found to have affected the flow of oxygen and nutrients from the placenta into the developing fetus.
Oxygen and nutrients struggled to reach the fetus, researchers say, after THC caused a decrease in the transfer of a glucose called GLUT-1. This means the mother’s body was unable to transfer glucose to the fetus during pregnancy, according to the study.
Another observation in the study found what appeared to be reduced blood flow from the mother to the fetus.
Researchers hope the study will help clinicians communicate the risks of cannabis use during pregnancy.