The demographic transition model is a conceptual framework developed in the early 20th century. The model is based upon the demographic changes that took place in Great Britain between approximately 1750 and 1950. The model tracks and roughly predicts the demographic pattern of population growth in four stages, tracking the fall of birth and death rates. The model is simple. In phase 1 or the high stationary period, the birth and death rates remain relatively high and equal. In stage 2, or the early expanding stage, the death rate drops dramatically while the birth rate remains high and steady. In stage 3, the late expanding stage, the death rate remains low while the birth rate plunges. In the fourth, or the low stationary stage, the birth rate has fallen to levels almost consistent with the death rate. It is important to keep in mind that the country's population will increase slowly but steadily throughout the transition process. While the model itself is easy to understand, the social and economic processes behind the transition are much more complicated. Western Europe and most of the other developed countries are at or even beyond the fourth stage, yet many undeveloped countries in Africa and Asia are still at the second stage or earlier. This discrepancy is important because the countries going through the transition presently are facing different and arguably larger challenges than the countries that passed through the transition before them. .
Stage one of the model is characterised by high birth and death rates. The population grows only slightly. The slow growth rate can be in part attributed to high infant and mother mortality at birth due to the lack of medical support available. The death rate can be attributed to the same reason, as many people were wary of doctors due to the ineffectiveness of the limited medicine available. At this time Great Britain was still a largely agrarian society.