> Today Quebec has the lowest provincial birthrate in Canada.
Not remotely true. As of 2016 Quebec has a fertility rate of 1.59 children per women which is higher than the Canadian average (1.54), Ontario (the largest province by far, 1.46) as well as BC (1.40) and the Atlantic provinces (1.42-1.58).
See https://www150.statcan.gc.ca/n1/pub/91-209-x/2018001/article...