Asteady population increase with slowed birthrates and death rates is which stage of population growth?

4th Phase of the Demographic Transition model

Explanation:

The 4th phase of the Demographic Transition is a result of the continuation of the phase 3 trends, ie, the declining birth rate stabilizes at low values and the mortality rate (which declines since the second phase) remains low as well. With this, the vegetative growth of the population is also low.

This phase is marked by the aging of the population, due to the fact that the average age in the countries that go through this period is relatively high. This aging is due to the high life expectancy (which is strictly related to low mortality), associated with the small number of children per couple.

When a country is in this phase, its Demographic Transition is deemed to have been terminated. Japan, Norway and Sweden are examples of nations in this group.