OTTAWA -- The Society of Obstetricians and Gynecologists is warning pregnant and breastfeeding women about the potential dangers of cannabis use.

The society points to evidence-based studies that suggest potential growth and development issues if cannabis is used while pregnant or breastfeeding.

That includes pre-term labour, low birth weight, lower IQ scores and impulsivity and hyperactivity in childhood.

The group says the main psychoactive component of cannabis -- THC -- crosses the placenta into fetal tissue and can also accumulate in breast milk. And that's regardless of whether cannabis is vaped, smoked, eaten, or in pill or topical form.

The organization announced its public awareness campaign on April 20, a date associated with pro-cannabis activism. The campaign includes two videos and material on Facebook, Instagram, and YouTube.

The doctors' group also pointed to research that suggests 70 per cent of pregnant and non-pregnant women believe there is a slight or no risk in using cannabis once or twice a week during pregnancy.

"Should cannabis become available for sale this summer, it is important that individuals be aware of the health risks, particularly for vulnerable populations such as pregnant women," the society's head, Dr. Jennifer Blake, said Friday in a release.