World Bank Document

lation is 765 million, the ultimate stationary popu- its net reproduction rate is other than 1, it was
lation assuming that NRR = 1 from 1985 onwards, assumed that fertility rates in these economies
is 1,349 million, and the population momentum is would regain replacement levels in order to make
1.76. estimates of the stationary population for them.
A population tends to grow even after fertility For the sake of consistency with the other estihas
declined to replacement level because past mates, the total fertility rates in the industrial econhigh
growth rates will have produced an age distri- omies were assumed to remain constant until
bution with a relatively high proportion of women 1985-90 and then to increase to replacement level
in, or still to enter, the reproductive ages. Conse- by 2010.
quently, the birth rate will remain higher than the International migration rates are based on past
death rate and the growth rate will remain positive and present trends in migration flow. The estifor
several decades. A population takes 50-75 mates of future net migration are speculative. For
years, depending on the initial conditions, before most economies the net migration rates were
its age distribution fully adjusts to the changed assumed to be zero by 2000, but for a few they
fertility rates. were assumed to be zero by 2025.
To make the projections, assumptions about The estimates of the hypothetical size of the stafuture
mortality rates were made in terms of tionary population and the assumed year of reachfemale
life expectancy at birth (that is, the number ing replacement-level fertility are speculative. They
of years a newborn girl would live if subject to the should not be regarded as predictions. They are
mortality risks prevailing for the cross-section of included to provide a summary indication of the
population at the time of her birth). Economies long-run implications of recent fertility and mortalwere
first divided according to whether their pri- ity trends on the basis of highly stylized assumpmary-school
enrollment ratio for females was tions. A fuller description of the methods and
above or below 70 percent. In each group a set of assumptions used to calculate the estimates is
annual increments in female life expectancy was available from the Bank publication: World Populaassumed,
depending on the female life expectancy tion Projections 1984-Short- and Long-term Estimates
in 1980-85. For a given life expectancy at birth, the by Age and Sex with Related Demographic Statistics.
annual increments during the projection period are
larger in economies having a higher primary- Table 20. Demographic and fertility-related
school enrollment ratio and a life expectancy of up indicators
to 62.5 years. At higher life expectancies, the increments
are the same.
The crude birth and death rates indicate the number
To project fertility rates, the first step was to esti- of live births and deaths per thousand population
mate the year in which fertility would reach in a year. They are from the same sources menreplacement
level. These estimates are speculative tioned in the note for Table 19. Percentage changes
and are based on information on trends in crude are computed from unrounded data.
birth rates (defined in the note for Table 20), total The total fertility rate represents the number of
fertility rates (also defined in the note for Table 20), children that would be born per woman, if she
female life expectancy at birth, and the peri'or- were to live to the end of her childbearing years
mance of family planning programs. For most and bear children at each age in accord with preeconomies
it was assumed that the total fertility vailing age-specific fertility rates. The rates given
rate would decline between 1980 and the year of are from the same sources mentioned in the note
reaching a net reproduction rate of 1, after which for Table 19.
fertility would remain at replacement level. For The percentage of married women of childbearing age
most countries in sub-Saharan Africa, and for a using contraception refers to women who are pracfew
countries in Asia and the Middle East, total ticing, or whose husbands are practicing, any form
fertility rates were assumed to remain constant for of contraception. These generally comprise male
some time and then to decline until replacement and female sterilization, intrauterine device (IUD),
level was reached; for a few they were assumed to condom, injectable and oral contraceptives, sperincrease
until 1990-95 and then to decline. micides, diaphragm, rhythm, withdrawal, and
In some countries, fertility is already below abstinence. Women of childbearing age are generreplacement
level or will decrease to below ally women aged 15-49, although for some counreplacement
level during the next 5 to 10 years. tries contraceptive usage is measured for other age
Because a population will not remain stationary if groups.
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