Population and Fertility

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Population and Fertility

• Ashry Gad Mohamed
• Prof. of Epidemiology

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Population Change

• Fertility

• Mortality

Migration
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Demographic Transition Model

• DTM is a hypothesis involving population changes
  over time
• As countries become more industrialized, first
  their death rates and then their birth rates
  decline
• According to the hypothesis, this transition
  occurs over 4 phases

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High Stationary (Pre-industrial Phase)

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

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Early Expanding (Transitional Phase)

• Industrialization begins.
• Food supply increases.
• Health care improves
• Death rate drops.
• Birth rate stays high
• Pop grows dramatically.
• India

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Late expanding

• Birth rate drops and approaches death rate
• Industrialization and modernization become
  widespread
• Pop growth slows
• Egypt, Turkey

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Low Stationary

• Low birth rate.
• Low death rate
• Stationary population
• Most industrized countries

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Declining

• Death Rate more than birth rate
• Decrease the total population.
• Germany

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Demographic Transition
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Age Structure Diagram
Green - Pre-reproductive years Dark Blue-
Reproductive years Light blue - Post-
reproductive years
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How is Population Affected by Birth and Death
Rates?

• 1- Rate of Natural Increase (RNI)
• Number of births number of deaths
• 
  X 100
• Estimated mid year population
• Birth and death rates are coming down worldwide
  but death rates have fallen more sharply than
  birth rates
• Growth Rate
• RNI Net migration rate

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Ave Crude Birth and Death Rates
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Annual Population Growth Rate
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Fertility Rates

• 1- Replacement Level Fertility (RLF)
• Number of children a couple must bear to replace
  themselves
• Slightly higher than 2 per couple (2.1 in
  developed and 2.5 in developing).
• Does reaching RLF mean an immediate halt in pop
  growth?
• No b/c so many future parents are alive

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2-Total Fertility Rate (TFR)

• An estimate of the average number of children a
  woman will have during child bearing years if
  between the ages of 15 and 49 she bears children
  at the same rate as women did this year
• KSA 6.2

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Fertility Rates

• In 2003
• Ave global TFR was 2.8 per woman
• 1.5 in developed (down from 2.5 in 1950)
• 3.1 in developing (down from 6.5 in 1950)
• Still far above global replacement level!
• UN population projections to 2050 vary depending
  upon worlds projected average TFR

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Decline in Total Fertility Rates
Fig 11-5
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Figure 11-6
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What factors affect TFR?

• Duration of marriage
• Importance of children in labor force
• Cost of raising and educating children
• Contraception
• Educational/employment opportunities for women
• Infant mortality rate
• Mother age
• Number of children in the family

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What factors affect death rates?

• Rapid increase in worlds pop due to decline in
  crude death rates (not births)
• More people started living longer b/c
• Increased food supplies and distribution
• Better nutrition
• Improved public heath (immunizations etc)
• Improved sanitation and hygiene)
• Safer water supplies

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Two Indicators of Overall Health of People in a
Country

• Life Expectancy
• Ave of years an infant can expect to live
• Global LE increased from 48 to 67 (76 in
  developed 65 in developing) 1955-2003
• In worlds poorest 55 yrs or less
• Infant Mortality Rate
• of babies out of 1000 that die before 1yr
• Usually indicates lack of food, poor nutrition,
  poor health care, and high incidence of disease
• From 1965 to 2003, IMR dropped from 20 to 7 in
  developed and 118 to 61 in developing
• Still means 8M infants die of preventable causes
  each year (22,000 per day)

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Human Life Expectancy (1999)
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Factors Affecting Birth and Death Rates in the
Demographic Transition

• Death Rates Decrease
• Improved Medicine
• Maternity Care
• Improved Sanitation
• Improved Hygiene
• Improved Water supply
• Improved Food/Nutrition
• Agriculture
• Food preservation
• Improved Transportation
• Cessation of Military Conflict

• Birth Rates Remain High
• Compensate for high infant mortality
• Assure care for elders
• Provide labor
• Cultural/Religious practices
• Prohibit Birth Control
• Favor large families
• Lack of contraceptives
• Lack of education _at_ family planning

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Education of women reduces the average number of
children per family
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3-General Fertility rate (GFR)

• Number of births/yL
• 
  X 100
• Number of females in child bearing age
• Disadvantages?

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4-Marital fertility rate (fecundity rate)

• Number of births/yL
• 
  X 100
• Number of married females
• in child bearing age

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5-Age specific fertility rate

• Number of births by females
• in specific age group
• 
  X 1000
• Number of females in the same
• Age group

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6-Crude birth rate (CBR)

• Number of births Y/L
• X
  1000
• Mid year population Y/L

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7-Cross reproduction rate

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

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Thank you