Significance of Demographic transition in Public Health Dr.Ayesha Babar Kawish

Demographic Transition In 1929 the American demographer Warren Thompson, observed changes in birth and death rates in industrialized societies over the past two hundred years or so and then formulated a model called “Demographic Transition” that describes population change over time.

DEMOGRAPHIC STAGES Describe changes in population size and composition due to increase or decrease in no of births and deaths

HIGH STATIONARY STAGE Birth rate is high, death rate high. They nullify each other’s effect no change in size of population.

STAGE 1 – HIGH STATIONARY Birth Rate and Death rate both high. Population growth is slow and fluctuating. Reasons : Birth Rate is high as a result of: Lack of family planning High Infant Mortality Rate Need for workers in agriculture Religious beliefs Death Rate is high because of: High levels of disease Famine Lack of clean water and sanitation Lack of health care Wars & Conflicts

STAGE 2 – EARLY EXPANDING Death Rate begins to decline. Birth Rate remains unchanged. Population begins to rise steadily. Reasons of decline in Death Rate: Improved health care (e.g. Smallpox Vaccine) Improved Hygiene (Water for drinking boiled) Improved sanitation Improved food production and storage Improved transport for food Decreased Infant Mortality Rates Typical of Britain in 19th century; Bangladesh; Nigeria South Asia, Africa

LATE EXPANSION STAGE Birth rate increase, death rate decreases, tremendous increase in population

STAGE 3 – LATE EXPANDING Birth Rate tends to fall. Death Rate declines still further. Population continues to grow. Reasons: Family planning available Lower Infant Mortality Rate Increased mechanization reduces need for workers Increased standard of living Changing status of women Typical of Britain in late 19th and early 20th century; China; Brazil, Pakistan.

LOW STATIONARY STAGE Birth rate low, death rate low, Nullify each others effect. no change in population size.

STAGE 4 – LOW STATIONARY Birth Rate and Death Rate both low. Population becomes stationary like in industrialized nations. Typical of USA; Japan; Britain These changes are reflected in the population structure.

DECLINING STAGE Birth rate lower than death rate. Negative growth in population.

STAGE 5 – DECLINING Birth rate lower than death rate. Population starts declining. Examples: Germany, Sweden and Hungry. Negative Growth Rate.

Demographic Transition Two demographic worlds Less-developed counties represent 80% of the world population, Richer countries tend to have negative growth rates. Growth Rate (%) Grading of population increase 0 ( Zero) 0 to 0.5 0.5 to 1 1 to 1.5 1.5 to 2.0 > 2 Stationary Growth (No Growth) Slow Growth Moderate Growth Rapid Growth Very Rapid Growth Explosive Growth ( Population explosion) OR Population Bomb

DEMOGRAPHIC TRANSITION 3 TYPES 1. Old balance Fertility Mortality 2. New balance 3. Imbalance

DEMOGRAPHIC TRANSITION A look at global demographic situation suggests that some countries have passed through high fertility and high mortality condition to a low fertility and mortality condition both aiming at low growth of population. These two conditions are referred as old & new balance, with an in-between period of imbalance as described below: OLD BALANCE HIGH FERTILITY HIGH MORTALITY (POOR HEALTH CONDITION , NOT COMPFORTABLE LIFE STYLE) LOW FERTILITY NEW BALANCE LOW MORTALITY GOOD HEALTH CONDITIONS, COMFORTABLE LIFE STYLE HIGH FERTILITY IMBALANCE LOW MORTALITY (PERIOD OF RAPID NATURAL INCREASE)

This growth is helpful for under populated nations which needs more manpower, expanding markets ; however it eventually results in too fast growth of population leading to economic, political and social chaos. a no. of developing countries e.g. Pakistan & many African countries are in this phase of demographic transition (Late Expanding)

Demographic gap is the difference between birth rate and death rate that develops when a country undergoes demographic transition In a demographic cycle, as the country develops and the living conditions improve, there is first a decrease in the death rate in the population But the birth rate continues to remain at a high level This results in a demographic gap and a resultant increase in the total size of population The demographic gap is maintained till the birth rate and death rates become equal and the population size becomes stable

Population Pyramids ( Demographic Transition Models) Stage 1 Stage 2 Stage 3 Stage 4 High stationary Early expanding Late expanding Late stationary IMPLICATIONS Both birth rates and Death rates are High population growth rates are slow but population Is usually restored Due to high birth rate. Short life expectancy Population starts to grow at an exponential rate due to fall in Crude Death Rate. More living In middle age. Life expectancy rises Infant mortality rate falls. Population continues to grow but at slower rate. Low C Death Rate. Dramatically declining Crude Birth Rate. Low Crude Birth Rate and Crude Death Rate Higher dependency ratio and longer life expectancy Crude Death Rate does Rise slightly because of The ageing population Scotland today. Japan, USA Scotland 1870 -1950 Algeria, Tunisia Morocco Scotland before 1760 New Guinea Remote parts of Amazonia Scotland 1760 - 1830 Republic of Congo There is some merit in including or considering a Stage 5 today with a declining population

According to Malthusian theory of population increase population increase in geometric ratio where as food supply increase in arithmetic ratio. This disharmony would lead to widespread poverty and starvation which would only be checked by natural occurrences such as disease, high infant mortality, famine, war or moral restraint. His main contribution is in the agricultural sector. According to this theory there are two steps to control the population, PREVENTIVE AND POSITIVE CHECK. preventive means control in birth rate, use of different methods to control birth and positive check means natural calamities, war etc. Arithmetic = 1,2,3,4,5 or 2,4,6,8, 3, 6, 9, 12 sequence Geometric= 1,2,4,8,16,32 16,8,4,2,1,1/2 ratio difference

DEMOGRAPHIC CYCLE Germany, Hungary (after effect of India in 1920-1930 Population Grows rapidly Germany, Hungary (after effect of II world war) India in 1920-1930 Population Becomes stationary Population Grows slowly Population declines Population stationary Many countries of S. Asia & Africa China, Singapur Pak in 1970

Demographic Transition Accompanying Economic and Social Development B Birth Rate Death Rate In the above graph, you can see there are distinctive periods of transitions associated with population stabilization. For instance, in pre-development periods, when there is a lack of medicine or mechanized agriculture, food often limits population growth. In these periods, there is a very high death rate (about 30 per 1,000 people), which includes people who die before they have a chance to reproduce. So a high birth rate is required to keep the population size stable. In the next phase, shown in the second column of the graph, a society develops better medical care and sanitation, and the death rate starts to fall. More people live into their reproductive years, so the birth rate remains high and may even increase. In the third phase, the death rate stabilizes and birth rates start to drop. The birth rate may drop for a variety of reasons - women have more access to education, or governments promote family planning, for example. Also, as a society industrializes, the labor of children is no longer needed to help the family survive, and there are other ways for people to be cared for in their old age than through their children. In the last phase of transition, represented by "developed" countries, birth and death rates stabilize. Notice, though, that the population size is greater overall than in the predevelopment phase. If an ever-increasing population is a societal ill, then theoretically the birth rate can adjust back down to where the population will again be stable.

Population Momentum The tendency of a population to continue to grow after replacement-level fertility has been achieved. A population that has achieved replacement or below replacement fertility may still continue to grow for some decades because past high fertility leads to a high concentration of people in the youngest ages. Total births continue to exceed total deaths. As these youth become parents. Thus it may take two or three generations (50-70 years) before each new birth is offset by a death in the population.

DEMOGRAPHIC TRAP Country with high population growth --high birth rate and low death rate. When a developing country moves into the 3rd stage of transition---death rates < 10/1000 people. Country’s economic growth unable to support needs of exploding population instead of economic development. Country cannot proceed onward to the final stage of post transition.

DEMOGRAPHIC WINDOW Period of time when the working age group population is particularly prominent. This window of opportunity lasts for 3-4 decades. Birth rates fall, age pyramid shrinks with lower proportions of young population (< 15s ) and dependency ratio decreases, e.g., as in East Asia. After a few decades, low fertility causes population to get older & thereby inflate the dependency ratio, e.g. as in Europe today.

ii) Percentage distribution of population by age-sex-location are helpful in understanding health and health care needs of various age groups by sex by location, for planning, designing, evaluation and effective implementation of various public health programs. For example : Vaccination and immunization program for children under 5 years of age, Mother and Child Health program for mother and new born, Family planning program, old age program, nutritional program etc.

iii) Determining the success or failure of health programs. iv) To describe the level of community health. v) To determine the leading causes of mortality and morbidity.

vi) To determine the relative importance of different fatal diseases with respective to age and sex. vii) To discover solution to health problems and find clues for public health challenges.

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