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POPULATION

DYNAMICS AND

HEALTHKai-Lit Phua,PHD

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DEMOGRAPHY

Scientific study of population

Births (Fertility)

Sickness (Morbidity)

Deaths (Mortality) Population movements (Migration)

Other e.g. abortion rates, divorce rates etc.

Scholars often focus on subtopics e.g. teenagefertility, immigrant fertility, infant mortality,maternal mortality

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DEMOGRAPHY

Composition of population --- ethnic, age, sex(also, how many are non-citizens)

Distribution --- % rural, % urban, % suburban. Also, how many citizens live overseas

Growth --- rapid growth, slow growth,population decline

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DEMOGRAPHY

Population is affected by fertility, mortalityand migration rates

Final population = Initial population +(Births – Deaths) + (Immigration – Emigration)

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AGE-SEX COMPOSITION OF A POPULATION

Depicted by the Population Pyramid

“Young” population: pyramid is triangular

“Ageing” population: pyramid becomes

more and more rectangular

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“YOUNG” POPULATION

% of total population under age 15 is high

Median age as low as 15 or 16

Due to high fertility

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“AGEING” POPULATION

Elderly rises from 5% to more than 20% of totalpopulation

Due mainly to low fertility e.g. Japan, Singapore

“Young-old” versus “old-old” More and more elderly women

More chronic & degenerative diseases

Multiple health problems are common in elderly people

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THE DEMOGRAPHIC TRANSITION

This refers to the change from:

High rates (births and deaths) toLow rates (births and deaths)

Death rates drop before birth rates: therefore, there is a

period of rapid population growth. This ends when birthrates finally drop.

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DEMOGRAPHIC TRANSITION

Falling death rates are due to better nutrition andhigher standards of living

Falling birth rates are due to social and economic

changes:

1) Women stay in school longer

2) More women work outside the home

3) Women marry later

4) Women postpone childbearing

5) People choose to have fewer kids

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(1) FERTILITY

Fertility rates differ by social variables:

Differ by religious group e.g. Catholic Church and

contraceptionDiffer by social class – lower classes tend to have higher

fertility

Differ by region – people in rural areas tend to have higher

fertilityDiffer by country – people in poor countries tend to have

higher fertility

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(1) FERTILITY

Fertility rates can be affected by:

Public policy e.g. some governments pressure couples to have fewerkids, other governments encourage them to have more!

Culture e.g. religion and contraception Economics e.g. expense of having kids in industrial versus

agricultural societies

Technology e.g. are effective contraceptive methods available?

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FERTILITY AND HEALTH

High fertility can increase maternal and childmortality

Continuous child-bearing can have a negative

impact on maternal health Closely-spaced births (<18 months apart) & low

birth weight babies (<2,500g) at higher risk

Illegal abortions and maternal mortality “Female genital mutilation” & maternal mortality

Sex-selective abortion in China and India

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FERTILITY AND HEALTH

Problem of teenage pregnancies in USA

STDs such as gonorrhea can lead to infertility inwomen

Use of condoms reduce transmission of STDSe.g. HIV/AIDS

Monogamous women at risk of being infected

with HIV by husbands and boyfriends

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INFERTILITY AND “ASSISTED

REPRODUCTION” Infertility = inability to conceive children

Options for infertile couples:

Adoption

In some societies: second spouse, or even divorce oreven abandonment of “infertile” spouse

Treatment for infertility

Ethical issues e.g. surrogate motherhood,

Baby M case in USA, sperm donors and sperm banks

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(2) MORBIDITY ANDMORTALITY

The Epidemiological Transition

This refers to the change in diseasepatterns from mostly infectious diseases tomostly chronic and degenerative diseases

Cancer, heart disease, stroke, injuries,diabetes, arthritis etc versus HIV/AIDS,SARS etc

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MEASURES OF MORTALITY

Infant mortality rate (deaths of babies under 1 year old)

Neonatal mortality rate (<28 days after birth)

Postneonatal mortality rate (between 28 days and 1 year

old)

IMR = Deaths of babies under 1 year X 1,000Total live births

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MEASURES OF MORTALITY

IMR = Neonatal Mortality Rate +Postneonatal Mortality Rate

Low Birth Weight (<2.5 kg at birth)greatly increases the risk of infantmortality

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OTHER MEASURES OFMORTALITY

Under 5 mortality rate

Life expectancy at birth

Age-specific mortality rates

Cause-specific mortality rates

Maternal mortality rate

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MEASURES OF MORBIDITY

Very important:

Incidence rate Prevalence rate

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INCIDENCE RATE

No. of NEW cases in fixed time period X 1,000

Population at risk

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PREVALENCE RATE

No. of people with a disease X 1,000

Population at risk

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(3) MIGRATION

Involuntary: slavery, ethnic persecution, wars,natural disasters, famines

Voluntary: to seek jobs (skilled or unskilled),to get an education, because of marriage, uponretirement

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Internal migration: within a country e.g. rural to urban International migration: skilled professionals to other

countries

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MIGRATION AND HEALTH

Migrants (workers, prostitutes, truck drivers) may spreadinfectious diseases e.g. HIV/AIDS, TB, diphtheria

Jet travel speeds up disease transmission

Migrants often live in urban slums and experience adjustmentproblems (these can affect their physical or mental health)

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THE END

THANK YOU

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Further reading

Adjustment of Hmong (Laotian hill tribe)refugees in America:

www.pbs.org/newshour/bb/asia/vietnam/hmong_5-4.html

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Biographical details

Kai-Lit Phua received his BA (cum laude) in Public Health & Population Studies from the University of Rochester and his PhD inSociology (Medical Sociology) from Johns Hopkins University. Healso holds professional qualifications from the insurance industry.

Prior to joining academia, he worked as a research statistician forthe Maryland Department of Health and Mental Hygiene and for theManaged Care Department of a leading insurance company inSingapore.

He was awarded an Asian Public Intellectual Senior Fellowship bythe Nippon Foundation in 2003.

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