Any reproducing organism population and its interaction with its offspring constitutes a Population Growth reinforcing loop.
Population interacting with birth
rate produces births. Births
are then added to the population making it larger.
This larger population will then interact with the birth
rate adding even more births.
It should be evident that this is a very naive representation of a population growth cycle. There are numerous additional influences that come into play in any model of a real environment.
This reinforcing loop may by virtuous or viscous depending on whether the species multiplying are members of your immediate family or flesh eating bacteria. There is a difference!