The natural population growth rate refers to the ratio, during a given period, usually one year, of the natural population increase to the average population of that same period, expressed per thousand. Natural population increase means the number of births minus the number of deaths.

The formula is:

Natural Population Growth Rate = (Annual Births - Annual Deaths) / Annual Average Population × 1000‰ = Birth Rate - Death Rate

Because this measure reflects births minus deaths, it does not capture population change caused by migration. Comparing provincial trends helps show where natural increase remains positive, where it is slowing, and where it has turned negative over time.