Transcript 10 - Fertility.ppt

Population
and
Fertility
Ashry Gad Mohamed
Prof. of Epidemiology
Population Change
 Mortality
Migration
 Fertility
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
High Stationary
(Pre-industrial Phase)
 Little pop growth.
 Harsh living conditions.
 High birth
 High death rate
 Central Africa
Early Expanding
(Transitional Phase)
 Industrialization begins.
 Food supply increases.
 Health care improves
 Death rate drops.
 Birth rate stays high
 Pop grows dramatically.
 India
Late expanding
 Birth rate drops and approaches death
rate
 Industrialization and modernization
become widespread
 Pop growth slows
 Egypt, Turkey
Low Stationary




Low birth rate.
Low death rate
Stationary population
Most industrized countries
Declining
 Death Rate more than birth rate
 Decrease the total population.
 Germany
Demographic Transition
Stage 2
Transitional
Stage 3
Industrial
Stage 4
Postindustrial
High
80
70
Relative population size
Birth rate and death rate
(number per 1,000 per year)
Stage 1
Preindustrial
60
50
Birth rate
40
30
Death rate
20
10
0
Total population
Low
Increasing Growth Very high
growth rate
growth rate
growth rate
Decreasing
growth rate
Low
Low
growth rate
Zero
growth rate
Negative
growth rate
Time
Fig. 11.18, p. 233
Age Structure Diagram
Green - Pre-reproductive years Dark Blue- Reproductive
years Light blue - Post- reproductive years
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
Ave Crude Birth and Death
Rates
Average crude birth rate
Average crude death rate
World
22
9
All developed
countries
11
10
All developing
countries
25
9
Developing
countries
(w/o China)
29
9
Annual Population Growth
Rate
Annual world
population growth
<1%
1-1.9%
2-2.9%
3+%
Data not
available
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
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
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 world’s projected
average TFR
Decline in Total Fertility
Rates
World
5 children per women
2.9
Developed
countries
2.5
1.5
Developing
countries
6.5
3.2
Africa
6.6
5.3
Latin
America
5.9
2.8
Asia
5.9
2.8
Oceania
3.8
2.4
North
America
3.5
Fig 11-5
2.0
Europe
2.6
1.4
1950
2000
Figure 11-6
Births per woman
<2
4-4.9
2-2.9
5+
3-3.9
Data not
available
Fig. 11.8, p. 242
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
What factors affect death
rates?
 Rapid increase in world’s 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
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 world’s 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)
Human Life
Expectancy
(1999)
Factors Affecting Birth and Death Rates
in the Demographic Transition
 Death Rates Decrease
 Birth Rates Remain High
 Improved Medicine
 Compensate for high
infant mortality
 Assure care for elders
 Provide labor
 Cultural/Religious
practices
 Maternity Care




Improved Sanitation
Improved Hygiene
Improved Water supply
Improved Food/Nutrition
 Agriculture
 Food preservation
 Improved Transportation
 Cessation of Military
Conflict
 Prohibit Birth Control
 Favor large families
 Lack of contraceptives
 Lack of education @
family planning
Education of women
reduces the average
number of children
per family
3-General Fertility rate (GFR)
Number of births/y&L
X 100
Number of females in child bearing age
Disadvantages?
4-Marital fertility rate (fecundity
rate)
Number of births/y&L
X 100
Number of married females
in child bearing age
5-Age specific fertility rate
Number of births by females
in specific age group
X 1000
Number of females in the same
Age group
6-Crude birth rate (CBR)
Number of births Y/L
X 1000
Mid year population Y/L
7-Cross reproduction rate
The total number of females births a
woman would have in her entire
reproduction life without considering
mortality.
Thank you