Universite Laval to conduct large-scale study on cannabis use during pregnancy

A new study led by researchers at Université Laval will attempt to fill gaps in scientific data on cannabis use during pregnancy and its effects on child development. 

A research team will use a $2.3 million grant from the Canadian Institutes of Health Research to follow a cohort of children until 30 months of age, and a $600,000 grant from the Fonds de recherche du Québec-Santé to analyze them until adulthood. 

Over the next five years, researchers will focus on the children's motor, language and behavioural development. Some aspects will be assessed by parents and others by scientists.

"There are very few contemporary studies that have looked at the effects of cannabis on child development," said Professor Gina Muckle of Université Laval's faculty of social sciences.

She says the handful of studies so far suggest an association between cannabis use during pregnancy and increased impulsivity, decreased concentration and impacts on intellectual functioning.

However, this data is of questionable reliability, as these studies were conducted before cannabis was legalized and sometimes involved women with other risk factors, such as hard drug use or inadequate or no pregnancy monitoring.

These studies also relied on women's self-reported data regarding their cannabis use, which opens the door to several recall errors.

It's these and other gaps that the new Université Laval study seeks to fill.

"The picture of female users has changed dramatically in this new legalization environment," said Muckle. "The majority of women in the general population who use cannabis do not use illegal drugs, the majority have a good pregnancy follow-up [...] So we don't know what the impact [of cannabis use] might be in that context."

Muckle and her colleague Richard E. Bélanger of the faculty of medicine hope to recruit about 4,000 pregnant women and their partners during the first trimester of pregnancy.

The clinical component of the project will be conducted at the CHU de Québec-Université Laval Research Centre by Dr. Emmanuel Bujold.

Cannabis exposure will be assessed through questionnaires and analysis of maternal hair samples, which will "allow us to have a better marker of fetal exposure," explained Muckle.

Researchers will then monitor the pregnancy's progress and the fetus's development.

The most recent data from the Quebec Cannabis Survey shows that in 2021, 43 per cent of young adults aged 21 to 24 had used cannabis in the past year. That number was 36 per cent for those aged 25-34.

"We don't know what proportion of these young adults who are going to use cannabis at the time of conception and then during pregnancy are going to maintain their use, so it may still be a pretty significant phenomenon," Muckle noted.

Data collected in 2018 from Toronto revealed that 14 per cent of women used cannabis in early pregnancy, "but we think that this phenomenon is considerably underestimated," said the researcher.

"We are convinced that we need new and updated data that reflect the picture of use or fetal exposure today to be able to better guide future parents."

This report by The Canadian Press was first published in French on Feb. 16, 2023.