Stage one of the demographic transition model is the most primitive of the stages where there is a high fluctuating birth and death rate. Because of this there is no great population growth. These countries or even tribes have very basic living standards such as those in the Amazon rainforest where they hardly have any education, medicaments or birth rates such that population is based on food supply, health of tribe members etc. Other factors involved are no family planning therefore many children or because of the faith of the people which may look at large families as a sign of verility etc.
In this stage of the demographic transition model there are a lot of births, however the death rate has gone down to about 20/1000 infants who die. This results in a rise in population due to the fact that more infants are surviving. Reasons for which more people may be surviving may be better health care, improved sanitation such as water etc, more transport and medical care as well as inventions relating to this. In other words this stage involves a slight modernisation in health care raising people's living standards as well as their life expectancy.
Stage three is the stage at which there is already a low death rate as well as a declining birth rate therefore leading to a slight increase in population. The reason for the fall in births may be due to family planning, better education, lower infant mortality rate, a more industrialised way of life and the want for more material possesions as well as women being able to go out to work. In other words these countries are in the final stages of becoming like the western countries such as the states and those in Europe.
Stage four is the one at which Switzerland is. There is a stable population whithout much change because both the death and birth rate are low and in some cases there are more deaths than births therefore leading to a possible stage five.