Population Population andand

Fertility Fertility

Ashry Gad MohamedAshry Gad Mohamed

Prof. of Epidemiology Prof. of Epidemiology

Population ChangePopulation Change

FertilityFertility

MortalityMortality

Migration

Demographic Transition ModelDemographic Transition Model

DTM is a hypothesis involving population DTM is a hypothesis involving population changes over timechanges over time

As countries become more industrialized, As countries become more industrialized, first their death rates and then their birth first their death rates and then their birth rates declinerates decline

According to the hypothesis, this According to the hypothesis, this transition occurs over 4 phasestransition occurs over 4 phases

High Stationary High Stationary ((Pre-industrial Phase)Pre-industrial Phase)

Little pop growth.Little pop growth. Harsh living conditions.Harsh living conditions. High birth High birth High death rateHigh death rate Central AfricaCentral Africa

Early Expanding Early Expanding ((Transitional Phase)Transitional Phase)

Industrialization begins.Industrialization begins. Food supply increases.Food supply increases. Health care improvesHealth care improves Death rate drops.Death rate drops. Birth rate stays highBirth rate stays high Pop grows dramatically.Pop grows dramatically. IndiaIndia

Late expandingLate expanding

Birth rate drops and approaches death Birth rate drops and approaches death rate rate

Industrialization and modernization Industrialization and modernization become widespreadbecome widespread

Pop growth slowsPop growth slows Egypt, TurkeyEgypt, Turkey

Low StationaryLow Stationary

Low birth rate.Low birth rate. Low death rateLow death rate Stationary populationStationary population Most industrized countriesMost industrized countries

DecliningDeclining

Death Rate more than birth rateDeath Rate more than birth rate Decrease the total population.Decrease the total population. GermanyGermany

Demographic TransitionDemographic Transition

Fig. 11.18, p. 233

Low

High

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Stage 1Preindustrial

Stage 2Transitional

Stage 3Industrial

Stage 4Postindustrial

Lowgrowth rate

Increasing Growthgrowth rate

Very highgrowth rate

Decreasinggrowth rate

Lowgrowth rate

Zerogrowth rate

Negativegrowth rate

Birth rate

Total population

Death rate

Time

Age Structure DiagramAge Structure Diagram

Green - Pre-reproductive years Dark Blue- Reproductive years Light blue - Post- reproductive years

How is Population Affected How is Population Affected by Birth and Death Rates?by Birth and Death Rates?

1- Rate of Natural Increase (RNI) =1- Rate of Natural Increase (RNI) = Number of births – number of deathsNumber of births – number of deaths X 100X 100 Estimated mid year population Estimated mid year population

Birth and death rates are coming down worldwide but Birth and death rates are coming down worldwide but death rates have fallen more sharply than birth ratesdeath rates have fallen more sharply than birth rates

Growth Rate =Growth Rate =RNI + Net migration rateRNI + Net migration rate

Ave Crude Birth and Ave Crude Birth and Death Rates Death Rates Average crude birth rate Average crude death rate

World

All developedcountries

All developingcountries

Developingcountries

(w/o China)

22

9

11

10

25

9

29

9

Annual Population Growth Annual Population Growth RateRate

<1%

1-1.9%

2-2.9%

3+%Data notavailable

Annual worldpopulation growth

Fertility RatesFertility Rates

1- Replacement Level Fertility (RLF)1- Replacement Level Fertility (RLF) Number of children a couple must bear to Number of children a couple must bear to

replace themselvesreplace themselves Slightly higher than 2 per couple (2.1 in Slightly higher than 2 per couple (2.1 in

developed and ~2.5 in developing).developed and ~2.5 in developing).

Does reaching RLF mean an immediate halt Does reaching RLF mean an immediate halt in pop growth?in pop growth?No b/c so many future parents are aliveNo b/c so many future parents are alive

2-Total Fertility Rate (TFR)2-Total Fertility Rate (TFR)

An estimate of the average number of An estimate of the average number of children a woman will have during child children a woman will have during child bearing years if between the ages of 15 and bearing years if between the ages of 15 and 49 she bears children at the same rate as 49 she bears children at the same rate as women did this yearwomen did this year

KSA 6.2KSA 6.2

Fertility RatesFertility Rates

In 2003:In 2003: Ave global TFR was 2.8 per womanAve global TFR was 2.8 per woman

1.5 in developed (down from 2.5 in 1950)1.5 in developed (down from 2.5 in 1950) 3.1 in developing (down from 6.5 in 1950)3.1 in developing (down from 6.5 in 1950)

Still far above global replacement level!Still far above global replacement level!

UN population projections to 2050 vary UN population projections to 2050 vary depending upon world’s projected depending upon world’s projected average TFR average TFR

Decline in Total Fertility Decline in Total Fertility RatesRates

World

Developedcountries

Developingcountries

Africa

LatinAmerica

Asia

Oceania

NorthAmerica

Europe

5 children per women2.9

2.51.5

6.53.2

6.65.3

5.92.8

5.92.8

3.82.4

3.52.0

2.61.4

1950 2000

Fig 11-5

Figure 11-6Figure 11-6

Fig. 11.8, p. 242

Births per woman

< 2

2-2.9

3-3.9

4-4.9

5+

Data notavailable

What factors affect TFR?What factors affect TFR?

Duration of marriageDuration of marriage Importance of children in labor forceImportance of children in labor force Cost of raising and educating childrenCost of raising and educating children ContraceptionContraception Educational/employment opportunities for Educational/employment opportunities for

womenwomen Infant mortality rateInfant mortality rate Mother ageMother age Number of children in the familyNumber of children in the family

What factors affect death What factors affect death rates?rates?

Rapid increase in world’s pop due to Rapid increase in world’s pop due to decline in crude death rates (not births)decline in crude death rates (not births)

More people started living longer b/c:More people started living longer b/c: Increased food supplies and distributionIncreased food supplies and distribution Better nutritionBetter nutrition Improved public heath (immunizations etc)Improved public heath (immunizations etc) Improved sanitation and hygiene)Improved sanitation and hygiene) Safer water suppliesSafer water supplies

Two Indicators of Overall Two Indicators of Overall Health of People in a CountryHealth of People in a Country Life ExpectancyLife Expectancy

Ave # of years an infant can expect to liveAve # of years an infant can expect to live Global LE increased from 48 to 67 (76 in developed; 65 in developing) Global LE increased from 48 to 67 (76 in developed; 65 in developing)

1955-20031955-2003 In world’s poorest =55 yrs or lessIn world’s poorest =55 yrs or less

Infant Mortality RateInfant Mortality Rate # of babies out of 1000 that die before 1yr# of babies out of 1000 that die before 1yr Usually indicates lack of food, poor nutrition, poor health care, and high Usually indicates lack of food, poor nutrition, poor health care, and high

incidence of diseaseincidence of disease From 1965 to 2003, IMR dropped from 20 to 7 in developed; and 118 to From 1965 to 2003, IMR dropped from 20 to 7 in developed; and 118 to

61 in developing61 in developing Still means 8M infants die of preventable causes each year (=22,000 per Still means 8M infants die of preventable causes each year (=22,000 per

day)day)

Human Life Expectancy

(1999)

Factors Affecting Birth and Death Rates Factors Affecting Birth and Death Rates in the Demographic Transitionin the Demographic Transition

Death Rates DecreaseDeath Rates Decrease Improved MedicineImproved Medicine

Maternity CareMaternity Care

Improved SanitationImproved Sanitation Improved HygieneImproved Hygiene Improved Water supplyImproved Water supply Improved Food/NutritionImproved Food/Nutrition

AgricultureAgriculture Food preservationFood preservation

Improved TransportationImproved Transportation Cessation of Military Cessation of Military

ConflictConflict

Birth Rates Remain High Birth Rates Remain High Compensate for high Compensate for high

infant mortalityinfant mortality Assure care for eldersAssure care for elders Provide laborProvide labor Cultural/Religious Cultural/Religious

practicespractices Prohibit Birth ControlProhibit Birth Control Favor large familiesFavor large families

Lack of contraceptivesLack of contraceptives Lack of education @ Lack of education @

family planningfamily planning

Education of women reduces the average number of children per family

3-General Fertility rate (GFR)3-General Fertility rate (GFR)

Number of births/y&LNumber of births/y&L

X 100X 100

Number of females in child bearing ageNumber of females in child bearing age

Disadvantages?Disadvantages?

4-Marital fertility rate (fecundity 4-Marital fertility rate (fecundity rate)rate)

Number of births/y&LNumber of births/y&L

X 100X 100

Number of married femalesNumber of married females

in child bearing agein child bearing age

5-Age specific fertility rate5-Age specific fertility rate

Number of births by females Number of births by females

in specific age groupin specific age group

X 1000X 1000

Number of females in the sameNumber of females in the same

Age groupAge group

6-Crude birth rate (CBR)6-Crude birth rate (CBR)

Number of births Y/LNumber of births Y/L

X 1000X 1000

Mid year population Y/LMid year population Y/L

7-Cross reproduction rate7-Cross reproduction rate

The total number of females births a The total number of females births a woman would have in her entire woman would have in her entire reproduction life without considering reproduction life without considering mortality.mortality.

Thank youThank you