Canadians, like most developed countries, already have a very low birth rate. If you want to reduce the growth of human population, you have to look at countries and regions where the birth rate is significantly higher than two children per woman.
If you are concerned about the carbon footprint of individual people, you need to look at where most of that carbon goes and what can be done about it. In Canada, the two major contributors are heating and car use, both of which would be reduced by transforming suburban single family home developments into walkable medium density mixed-use neighborhoods.