Depicted here in four stages, and based on the history of the western world, the demographic transition enables us to view population growth in relation to changes over time in death or mortality rates and birth or fertility rates.

During stage 1, both the death rate and the birth rate are high. But the birth rate is constant, while the death rate fluctuates in the face of such manmade and natural disasters as famines, floods, pestilence, and wars.

During stage 2, the death rate begins a sharp decline due to major improvements in living standards attributable to industrialization. Any decline in the birth rate occurs close to the end of this stage. The large gap between the birth rate and the death rate accounts for the population explosion.

During stage 3, the birth rate falls closer to the death rate as people start controlling their fertility and limiting family size in recognition that most of their children will actually survive into adulthood, and as children become more expensive to raise largely because of increasing educational demands stemming from the industrialization process. A declining need for farm labor and parental support in old age has also depressed fertility.

In stage 4, the final stage, birth rates and death rates are both low. But in contrast to stage 1, birth rates fluctuate, indicative of fertility control as people alter their reproduction according to socioeconomic changes.

England was the first country to pass through the demographic transition. This took approximately 200 years. Some other countries, such as Japan, which started the process rather later than England, completed their passage through the transition in less than half that time.