If birth rates fall below the replacement level, than a country is in which stage of demographic transition?

Fourth Stage

Explanation:

During the fourth stage of demographic transition, the birth rates with in a population fall below the level of replacement and thus the population of such countries starts shrinking. This was once a common scenario in countries like Japan, Italy and Germany. The economy sees a down fall as the ageing population increases with no replacement of it in near by future.

Mostly the developed nations after the post industrial age are  facing this situation.