DEMOGRAPHY-PRINCIPLES, CYCLE, VITAL STATISTICS

Community medicine
Public health

1. DEMOGRAPHY Principle, Cycle, Vital Statistics Dr. Pretty venis Senior resident Department of community medicine smmchri

2. Definition Demography is defined as the study of human populations in a given area, usually a country, during a given year, with reference to size , composition , behaviour and distribution . Size : Total no. of persons residing in the country. Composition : Quality of the population. Eg : Age, sex, literacy level etc. Behaviour : Growth of the population over a period of decades. Distribution : Density of the population per sq.km

3. Demographic cycle The trend of population growth in a country undergoes changes in a step-wise manner STAGES OF DEMOGRAPHIC CYCLE

4. Stages of Demographic cycle Birth rate Death rate Population stationary Population grows slowly Population grows rapidly Population becomes stationary Population declines High stationary stage Early expanding stage Late expanding stage Low stationary stage Stage of decline Birth and death rates Demographic stages  Population growth  Pre-modern times Slow population growth Very high BR & DR South Asia. Africa Population growth + BR unchanged; DR starts decline Developing countries- India, China, Singapore Population growth + Further decline in DR; BR tends to fall; BR> DR Developed countries Low population growth Low BR & DR (BR=DR) Germany, Hungary Decline in population growth BR<DR Demographic gap

5. Indian context 1901-1921 High stationary stage

6. Indian context 1921-1971 Early expanding stage

7. Indian context 1971-2011 Late expanding stage

8. Sources of Demographic data Census Vital events registration Surveys Sample Registration System (SRS)

9. Epidemiological Transition The changing pattern of morbidity and mortality occurring all over the world over the past centuries seen in human history with variations in time and pace is known as “Epidemiologic/ Epidemiological transition”. - Abdel Omran Epidemiologist (1971)

10. Stages of Epidemiologic transition

11. Population pyramid When the breakdown of population is represented either as numbers or age percentages, according to different ages and sexes in the form of a horizontal bar diagram, it takes the shape of a ‘pyramid’, which is called “population pyramid” Requires : Age-sex specific death rate Age-specific sex ratio Standardization of death rate

12. Population pyramid- India

13. Sex ratio Sex ratio is defined as the number of women for every 1000 men. Causes of low sex ratio: Strong male child preference Gender inequalities Neglect of girl child Female infanticide/ foeticide High MMR India- 899 (SRS 2018) Tamil Nadu- 908 (SRS 2018)

14. Dependency ratio Dependency load/ Total dependency ratio/ Societal dependency ratio. Expressed per 100 adults. The ratio between the adults (economically productive 16-45 years) and the dependants ( children below 15 years and elderly above 65 years).

15. Dependency ratio Total dependency ratio = Children 0-15years + Population >65 years x 100 Population of 16-65 years Young age dependency ratio & Old age-dependency ratio India- 8.1% (2011)

16. Density of population Ratio between population and surface (land) area. India: 382/sq.km (2011)

17. Urbanization "Towns (places with municipal corporation, municipal area committee, town committee, notified area committee or cantonment board); also, all places having 5,000 or more inhabitants, a density of not less than 1,000 persons per square mile or 390 per square kilometre , pronounced urban characteristics and at least three fourths of the adult male population employed in pursuits other than agriculture “ Mumbai (12.69m) Delhi (10.92m) Bengaluru(5.104m) Kolkata (4.63m) Chennai (4.328m)

18. Family size Total no. of children a woman has borne at a point in time during her child bearing age (15-45years). Depends on: Duration of marriage Education of couple No. of live births Contraception method Socio-economic status

19. Literacy level Literacy means ability to read and write any language with understanding. India- 74.04 (2011) Tamil Nadu- 80.33 (2011)

20. Literacy rate Crude literacy rate = No. of literate persons x 100 Total population Effective literacy rate = No. of literate persons aged 7 and above x 100 Total population aged 7 and above

21. Life expectancy Best indicator of a country’s level of development and overall health status of the population. Japan leads with 81 and 87 years for males and females respectively. India: Males- 68 years Females- 70 years (2020) Average no. of years which a person of that age may expect to live, according to the mortality pattern prevalent in that country.

22. Vital statistics The term “vital statistics” refers to the study of vital events such as births, deaths, diseases, marriages and divorces. These include: Birth rate Death rate Growth rate Life expectancy at birth Mortality and fertility rates

23. Birth rate Birth rate = Number of live births during the year X 1000 Estimated mid-year population India= 19.5

24. Growth rate Growth rate Rating No growth Stationary population <0.5 Slow growth 0.5 – 1.0 Moderate growth 1 – 1.5 Rapid growth 1.5 – 2 Very rapid growth >2 Explosive growth

25. General fertility rate (GFR ): GFR = Number of live births in an area during the year X 1000 Mid-year female population age (15-44) in the same area in the same year India= 67

26. Age- specific fertility rate (ASFR) ASFR = No. of live births in a particular age group x 1000 Mid-year female population of the same age group

27. Total fertility rate (TFR) Average number of children a woman would have if she were to pass through her reproductive years bearing children at the same rates as the women now in each group. TFR = 5 X Σ ASFR 1000 Gives family size. India= 2

28. Gross Reproduction Rate Average number of girls that would be born to a mother - current fertility pattern and no mortality. GRR = 5 X Σ ASFR for female live births 1000

29. Marriage rate Crude marriage rate = No. of marriages within 1 year x 1000 Mid-year population General marriage rate = No. of marriages within 1 year x 1000 No. of unmarried persons aged 15-49 years

30. Summary Demography- study of human populations. Demographic cycle- 5 stages India- Late expanding stage (Stage 3) Vital events- births, deaths, diseases, marriage, divorce