Model of population cycle

The model of demographic transition progresses in four stages:

-Old or preindustrial demographic regime: it is characterized by high mortality and natality rates. Sometines Mortality rate is higher than natality rate, therefore there is a negative natural increase.

-First transition: keep the high natality rate, but mortality decrease, because of andvances in sanitation and health care.

-Second transition: the natality rate begins to decline, but mortality is still down, so there is balance.

-Modern demographic regime: mortality and natality are very low and sometimes natality rate falls so much that there is a negative natural increase.

The model of demographic transition progresses in four stages: