Pot smoking during pregnancy causes low birth weight in babies, London research finds

By Dale Carruthers

Women who use marijuana while pregnant are more at risk of giving birth to underweight babies, London researchers say.

The finding announced Thursday is part of the first large-scale study in Canada to establish a link between cannabis use and low birth weights.

The research comes on the heels of the federal government’s introduction of legislation to legalize and regulate marijuana by next year.

Using data from a five-year period at the London Health Sciences Centre, the researchers found pot-using pregnant women are nearly three times more likely than their non-cannabis-using counterparts to have an underweight infant.

Low birth weight — defined in the study as less than 2.5 kg — can lead to a slew of serious health problems, including respiratory problems such as asthma and poor cognitive development during childhood. Low-weight infants also are more at risk of developing Type 2 diabetes, hypertension and cardiovascular disease.

The researchers looked at a wide variety of other factors that could contribute to birth outcomes, such as demographics, in a bid to determine whether socio­economic status was related.

But they found socioeconomic status — measured by median neighbourhood income — had minimal influence on birth outcomes.

Researchers from Western University, the Lawson Health Research Institute and Brescia University College collaborated on the study, entitled Socioeconomic status and adverse birth outcomes: A population-based Canadian sample, which was published in the Journal of Biosocial Science.