POPULATION POPULATION DYNAMICS AND DYNAMICS AND

HEALTHHEALTHKai-Lit Phua, PhD FLMIKai-Lit Phua, PhD FLMI

Associate ProfessorAssociate ProfessorSchool of Medicine & Health School of Medicine & Health

SciencesSciencesMonash University MalaysiaMonash University Malaysia

Biographical details Biographical details

Kai-Lit Phua received his BA (cum laude) in Public Health & Kai-Lit Phua received his BA (cum laude) in Public Health & Population Studies from the University of Rochester and his Population Studies from the University of Rochester and his PhD in Sociology (Medical Sociology) from Johns Hopkins PhD in Sociology (Medical Sociology) from Johns Hopkins University. He also holds professional qualifications from University. He also holds professional qualifications from the insurance industry.the insurance industry. Prior to joining academia, he worked as a research Prior to joining academia, he worked as a research statistician for the Maryland Department of Health and statistician for the Maryland Department of Health and Mental Hygiene and for the Managed Care Department of a Mental Hygiene and for the Managed Care Department of a leading insurance company in Singapore. leading insurance company in Singapore.

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

DEMOGRAPHYDEMOGRAPHY Scientific study of population Scientific study of population

Births (Fertility)Births (Fertility) Sickness (Morbidity)Sickness (Morbidity) Deaths (Mortality)Deaths (Mortality) Population movements (Migration)Population movements (Migration) Other e.g. abortion rates, divorce rates etc.Other e.g. abortion rates, divorce rates etc.

Scholars often focus on subtopics e.g. teenage Scholars often focus on subtopics e.g. teenage fertility, immigrant fertility, Malay fertility, infant fertility, immigrant fertility, Malay fertility, infant mortality, maternal mortalitymortality, maternal mortality

DEMOGRAPHYDEMOGRAPHY

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

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

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

DEMOGRAPHYDEMOGRAPHY

Population is affected by fertility, Population is affected by fertility, mortality and migration ratesmortality and migration rates

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

AGE-SEX COMPOSITION OF AGE-SEX COMPOSITION OF A POPULATIONA POPULATION

Depicted by the Population PyramidDepicted by the Population Pyramid

““Young” population: pyramid is Young” population: pyramid is triangulartriangular

““Ageing” population: pyramid Ageing” population: pyramid becomes more and more rectangular becomes more and more rectangular

““YOUNG” POPULATIONYOUNG” POPULATION

% of total population under age 15 is % of total population under age 15 is highhigh

Median age as low as 15 or 16Median age as low as 15 or 16

Due to high fertilityDue to high fertility

““AGEING” POPULATIONAGEING” POPULATION

Elderly rises from 5% to more than 20% of Elderly rises from 5% to more than 20% of total populationtotal population

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

““Young-old” versus “old-old”Young-old” versus “old-old” More and more elderly womenMore and more elderly women More chronic & degenerative diseasesMore chronic & degenerative diseases Multiple health problems are common in Multiple health problems are common in

elderly peopleelderly people

THE DEMOGRAPHIC THE DEMOGRAPHIC TRANSITIONTRANSITION

This refers to the change from:This refers to the change from:

High rates (births and deaths) toHigh rates (births and deaths) to

Low rates (births and deaths)Low rates (births and deaths)

Death rates drop before birth rates: Death rates drop before birth rates: therefore, there is a period of rapid therefore, there is a period of rapid population growth. This ends when birth population growth. This ends when birth rates finally drop. rates finally drop.

DEMOGRAPHIC TRANSITIONDEMOGRAPHIC TRANSITIONFalling death rates are due to better nutrition Falling death rates are due to better nutrition

and higher standards of livingand higher standards of living

Falling birth rates are due to social and Falling birth rates are due to social and economic changes:economic changes:

1) Women stay in school longer1) Women stay in school longer2) More women work outside the home2) More women work outside the home3) Women marry later3) Women marry later4) Women postpone childbearing4) Women postpone childbearing5) People choose to have fewer kids5) People choose to have fewer kids

(1) FERTILITY(1) FERTILITY

Fertility rates differ by social variables:Fertility rates differ by social variables:Differ by religious group e.g. Catholic Differ by religious group e.g. Catholic

Church and contraceptionChurch and contraceptionDiffer by social class – lower classes Differ by social class – lower classes

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

tend to have higher fertilitytend to have higher fertilityDiffer by country – people in poor Differ by country – people in poor

countries tend to have higher fertilitycountries tend to have higher fertility

(1) FERTILITY(1) FERTILITY

Fertility rates can be affected by:Fertility rates can be affected by:

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

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

industrial versus agricultural societiesindustrial versus agricultural societies Technology e.g. are effective contraceptive Technology e.g. are effective contraceptive

methods available?methods available?

FERTILITY AND HEALTHFERTILITY AND HEALTH

High fertility can increase maternal and child High fertility can increase maternal and child mortalitymortality

Continuous child-bearing can have a negative Continuous child-bearing can have a negative impact on maternal healthimpact on maternal health

Closely-spaced births (<18 months apart) & low Closely-spaced births (<18 months apart) & low birth weight babies (<2,500g) at higher riskbirth weight babies (<2,500g) at higher risk

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

mortalitymortality Sex-selective abortion in China and IndiaSex-selective abortion in China and India

FERTILITY AND HEALTHFERTILITY AND HEALTH

Problem of teenage pregnancies in Problem of teenage pregnancies in USAUSA

STDs such as gonorrhea can lead to STDs such as gonorrhea can lead to infertility in womeninfertility in women

Use of condoms reduce transmission Use of condoms reduce transmission of STDS e.g. HIV/AIDSof STDS e.g. HIV/AIDS

Monogamous women at risk of being Monogamous women at risk of being infected with HIV by husbands and infected with HIV by husbands and boyfriends boyfriends

INFERTILITY AND “ASSISTED INFERTILITY AND “ASSISTED REPRODUCTION”REPRODUCTION”

Infertility = inability to conceive childrenInfertility = inability to conceive children

Options for infertile couples:Options for infertile couples: AdoptionAdoption In some societies: second spouse, or even divorce In some societies: second spouse, or even divorce

or even abandonment of “infertile” spouseor even abandonment of “infertile” spouse Treatment for infertilityTreatment for infertility

Ethical issues e.g. surrogate motherhood,Ethical issues e.g. surrogate motherhood, Baby M case in USA, sperm donors and sperm Baby M case in USA, sperm donors and sperm

banks banks

(2) MORBIDITY AND (2) MORBIDITY AND MORTALITYMORTALITY

The Epidemiological TransitionThe Epidemiological Transition

This refers to the change in disease This refers to the change in disease patterns from mostly infectious patterns from mostly infectious diseases to mostly chronic and diseases to mostly chronic and degenerative diseasesdegenerative diseases

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

MEASURES OF MORTALITYMEASURES OF MORTALITY

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

Neonatal mortality rate (<28 days after Neonatal mortality rate (<28 days after birth)birth)

Postneonatal mortality rate (between 28 Postneonatal mortality rate (between 28 days and 1 year old)days and 1 year old)

IMR = IMR = Deaths of babies under 1 yearDeaths of babies under 1 year X 1,000 X 1,000

Total live birthsTotal live births

MEASURES OF MORTALITYMEASURES OF MORTALITY

IMR = Neonatal Mortality Rate + IMR = Neonatal Mortality Rate + Postneonatal Mortality RatePostneonatal Mortality Rate

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

OTHER MEASURES OF OTHER MEASURES OF MORTALITYMORTALITY

Under 5 mortality rateUnder 5 mortality rate

Life expectancy at birthLife expectancy at birth

Age-specific mortality ratesAge-specific mortality rates

Cause-specific mortality ratesCause-specific mortality rates

Maternal mortality rate Maternal mortality rate

MEASURES OF MORBIDITYMEASURES OF MORBIDITY

Very important:Very important:

Incidence rateIncidence rate Prevalence rate Prevalence rate

INCIDENCE RATEINCIDENCE RATE

No. of NEW cases in fixed time periodNo. of NEW cases in fixed time period X X 1,0001,000

Population at riskPopulation at risk

PREVALENCE RATEPREVALENCE RATE

No. of people with a diseaseNo. of people with a disease X X 1,0001,000

Population at riskPopulation at risk

(3) MIGRATION(3) MIGRATION Involuntary: slavery, ethnic persecution, Involuntary: slavery, ethnic persecution,

wars, natural disasters, famineswars, natural disasters, famines

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

------------------------------------------------------------ Internal migration: within a country e.g. Internal migration: within a country e.g.

rural to urbanrural to urban International migration: skilled professionals International migration: skilled professionals

to other countriesto other countries

MIGRATION AND HEALTHMIGRATION AND HEALTH

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

Jet travel speeds up disease transmissionJet travel speeds up disease transmission

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

Further readingFurther reading

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

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

THE ENDTHE END

THANK YOUTHANK YOU