Demographic transition

• Demographic transition is the changes in birth and death rates over time.
• Stage one of the demographic transition model includes high birth and death rates.
• High birth rates (as seen in stages 1 and 2) are due to lack of family planning and availability of contraceptives, high infant mortality rate which leads to women's having more children, and gender bias- as some families continue to have children until they have a son.
• Stage two includes a continued high birth rate but death rates start to fall.
• In stage three, birth rates start to fall, and death rates continue to fall.
• In stage four, the birth rate is low, and the death rate is low.
• In stage five, the birth rate is low and the death rate increases.
• Some reasons for high death rates (as shown in stage one) include: poor health care, disease, famine, and poor water and sanitation.
• Some reasons for low birth rates (as shown in stages three, four and five) include improved family planning, the empowerment of women, and improved health care.
• Reasons for low death rates (as shown in stages two, three, four, and five) include good health care and a reliable food supply.
• Natural increase is the growth in population as a result of birth rates exceeding death rates.
• Fertility rates are the number of children a woman has per lifetime.
• Life expectancy is the average number of years a person is expected to live calculated at birth.
• Dependancy ratio is a measure of non-workers divided by the workers.
• Population structure is the distribution of individuals within a population, including the number of individuals of each age class and sex.