Continues to Grow, and to Grow Older
At the beginning of the 20th
century, the worlds population was approximately 1.5 billion; by 1960 it had
doubled; and by late 1999, it had quadrupled to 6 billion. The global population is
unlikely ever again to grow as fast as it has in the last few decades and particularly the
past 12 years, in which a billion people were added.
Annual additions to the global population rose from 47 million per year in
19501955 to a peak of 86 million in 19851990. This unprecedented growth was
the net result of faster declines in mortality than in fertility, both from initially high
levels. As a consequence, the fourth, fifth and sixth billion marks in global population
were achieved in only 14, 13 and 12 years, respectively.3
Today, a "demographic transition" from high fertility and mortality to low
fertility and mortality is under way or has already occurred in much of the world. In many
respects, the less-developed regions are now about halfway through this transition,
approximately where the more-developed regions were a half-century ago.
Death Rate Cut by Half
The most important story behind the rapid rise from 3 to 6 billion people since 1960 is
the unprecedented drop in mortality. This trend actually began in the 19th and early 20th
century, but intensified after World War II as basic sanitation, clean drinking water and
modern health care became more available in larger areas of the world. Since 1950, the
death rate has been cut in half, from about 20 to fewer than 10 deaths per year per
thousand people. At the same time, average global life expectancy has risen from 46 to 66
The worlds population is healthier from infancy through old age than it ever has
been. Global infant mortality has fallen by two thirds since 1950, from 155 per thousand
live births to 57 per thousand; this rate is projected to be reduced by a further two
thirds by 2050. Maternal mortality has also declined, but much more slowly and less
generally (see Chapter 3). Other promising health trends include improvements in
immunization levels and health education.
One positive effect of lengthening life-spans and better medical treatment has been
that the annual number of deaths actually fell by more than 10 per cent between 1955 and
1975 even as nearly 1.5 billion people were added to the world population. Subsequently
the number of deaths began to increase. The current number of deaths per year, 52 million,
is the same as in 1950, when the population was less than half the size it is today.
Death rates have declined substantially in the less-developed regions since 1950, but
have remained roughly constant in the more-developed regions because of their greater
proportion of older people.
Fertility is Declining, but Unevenly
The number of births per year rose from 98 million in 1950 to a peak of 134 million in the
late 1980s, and is projected to remain just under 130 million for the next 20 years while
death rates slowly rise as the global population ages.
Although only a very few countries have declining populations, 61 countries (with about
44 per cent of the worlds population) already have below-replacement fertility rates
(less than 2.1 births per woman). The number of such countries is projected to grow to 87
by 2015, encompassing about two thirds of the worlds population.
On the other hand, in 2050, 130 countries will still have positive growth rates, 44 of
them above 1 per cent per year, about the rate observed in more-developed regions in 1965.
In 1950-1955, the average fertility rate in the more-developed regions was 2.8 children
per woman; it has since dropped to 1.6 and is projected to begin a slow rise, to 1.8, by
the middle of next century. In the less-developed regions, the fertility rate was almost
6.2 in 1950; it was slightly less than 3 by 1999, and is projected to fall to less than
2.1 by 2045.
Death rates have fallen by half since
accounting for much of the rapid growth of world population.
Fertility has declined most quickly in Latin America and Asia, less rapidly in North
Africa and the Middle East, and much more slowly in sub-Saharan Africa. Asias
fertility fell sharply in the last 50 years, from 5.9 to 2.6 children per woman.
Sub-Saharan Africas has dropped much more slowly, from 6.5 to 5.5. Latin America and
the Caribbean have seen a decline from 5.9 to 2.7, North Africa and Western Asia from 6.6
Europes fertility rate fell from 2.6 to 1.4, well below replacement level. On the
other hand, Northern Americas fertility fell from 3.5 in 1950-1955 to 1.8 in the
late 1970s, and then rebounded to the 1.9 to 2.0 range, where it has remained. It is
projected to stay around 1.9 to the middle of the 21st century.
Variations between and within regions, and among different population groups within
countries, remain considerable. Some nations, such as Brazil and the Republic of Korea,
have moved swiftly to near-replacement level or below; others, such as Nigeria and
Guatemala, have seen only a slight fall in fertility rates. However, the pace of decline
has varied dramatically in different parts of both Brazil and Nigeria.
Hopes of finding a simple and consistent explanation for the demographic transition 4
have been repeatedly dashed by the realities of data on local experiences.5 In fact, there is no tight statistical link between
development indicators and fertility rates, and the reasons for fertility decline are
widely debated by demographers, economists and policy makers. While development is still
considered an important factor, it remains unclear why fertility transitions occur earlier
in some places than others. The pace of development does not appear to affect the
initiation or the rate of fertility transition. However, once a transition has begun,
fertility declines more rapidly in countries with higher levels of development.6
Helping women and men to realize their family size desires
It seems clear that the family size desires of men and women are influenced by a variety
of factors: mortality declines; increased social opportunity, especially for women;
employment opportunities; incomes; and educational access. Women and men cannot realize
these desires, however, without the means to translate social opportunity and choice into
action. The creation and progressive strengthening of population programmes over the last
30 years 7 along with the
development and distribution of more-effective and safer forms of contraception has
been a crucial catalyst in reducing fertility rates.8
Population programmes have been given credit for about half the decline in fertility since
Since the ICPD, they have adopted an approach based on individual rights and needs.
Population programmes have been crucial
in reducing fertility rates in the past 30 years.
The spread of information about family planning techniques and new ideas about social
issues including the rights of women to reproductive health and equality of
opportunity facilitates the fertility transition.10
Discussion and debate among relatives, friends and neighbours, the diffusion of ideas
between communities, and mass media images trigger changes in preferences and fertility
behaviour. This may explain why fertility changes often occur more rapidly in countries
where various channels connect communities and individuals, and more slowly where such
social interaction is more difficult. If this is the case, improving communications could
help to speed up the fertility transition where it has been slow.11
Predicting what will happen at the end of the fertility transition in a particular
country whether fertility will stabilize at below, near or above replacement level,
or will bounce back upwards or have some other unstable pattern remains a critical
challenge for demographers.
Lower Population Projections:
Good News and Bad
The United Nations Population Divisions latest projection for global population
in 2050, 8.9 billion (medium variant), is substantially lower than its 1996 projection of
9.4 billion. In response, some commentators have raised concerns about "missing"
people. This is misleading.
The major reason for the lower projection is good news: global fertility rates have
declined more rapidly than expected, as health care, including reproductive health, has
improved faster than anticipated, and men and women have chosen to have smaller families.
About one third of the reduction in long-range population projections, however, is due
to increasing mortality rates in sub-Saharan Africa and parts of the Indian subcontinent.
The most important factor is HIV/AIDS, which is spreading much faster than previously
In addition, United Nations demographers have adopted more refined projection
techniques. Formerly, it was assumed that countries with below-replacement fertility rates
would return to replacement levels by 2050. The current assumption is that these countries
will have fertility rates of 1.7 to 1.9 births per woman (rather than 2.1) by 2050.
Changing assumptions about future fertility
In late 1998, the United Nations Population Division released its latest population
projections for the world, regions and countries through 2050 (see page 3). The Population
Division produces new projections every two years based on updated population data and
revisions in projection methodology. In the case of the 1998 Revision, both factors had a
substantial impact on the long-range projections.12
It is now projected that the global population will rise to between 7.3 and 10.7
billion by 2050; the medium variant projection, considered most likely, is 8.9 billion.
The key assumptions that create these results are global fertility rates, which are
projected to fall to between 2.5 and 1.6 births per woman by 2050. Under the medium
variant scenario, it is assumed that the fertility rate for every country in the
less-developed regions will drop to exactly 2.1 by 2050. For the more-developed regions,
national fertility rates are projected to reach between 1.7 and 1.9, depending on the
These assumptions point out the inherent uncertainties of population projections. The
United Nations projections have a record of successive adjustment to new information and
considerable long-term accuracy. However, it does not seem very likely that the Congo,
Nicaragua and Kazakhstan, with current fertility rates of 6.1, 4.4, and 2.3 births per
woman, respectively, will all have identical fertility rates of 2.1 in 2050. Similarly, it
is by no means certain that Italys fertility rate will rise from 1.2 to 1.7, or the
United States rate will drop from 2.0 to 1.9 by 2050, as the medium variant
projection assumes. National fertility rates will remain unpredictable over the long run.
Demographers, at institutions including the United Nations, are undertaking analyses to
improve or place scientific certainty bounds around projection scenarios.13
Education Levels and Fertility Declines
Throughout the developing world, literacy and years of schooling have increased for both
males and females over the last four decades.14
Demographers and sociologists have observed that improved education for women and girls is
closely related to improvements in health and to falling fertility rates.
Enrolment ratios have increased since 1960 in all regions and at all education levels,
especially at the primary level. 15 In
sub-Saharan Africa, however, primary school enrolment was still only 75 per cent in 1995
and has actually decreased since 1980. Enrolment has also declined recently in other
countries affected by financial crises.16
In low- and middle-income countries, 53 per cent of the relevant age group were
enrolled in secondary schools in 1995, up from 41 per cent in 1980. This compares poorly
with the high-income countries, where virtually all children have some secondary
education, and 35 per cent have some tertiary education (college and graduate school).
The limited data available on years of schooling illustrate the stark contrasts that
persist. For instance, in Burundi, men and women have had, on average, 5 and 4 years of
schooling, respectively. In Costa Rica, those numbers are 10 and 9 years, respectively; in
Canada, 18 and 17 years.
There is still a significant gender gap among both teachers and pupils in low-income
countries, but the situation is improving: 42 per cent of students in 1980 were female, 44
per cent in 1995; 32 per cent of teachers in 1980 were female, 39 per cent in 1995. In
middle- and high-income countries, the gender balance for pupils and teachers is much
closer men still outnumber women in both groups, but only by a few percentage
To foster the social development of girls, some countries have begun to promote
girls education through waiving fees, or providing a small payment or food
allocation for girls attendance, and by adapting the school system to facilitate
their participation. Since 1990, the Bangladesh Rural Advancement Committee has, for
example, created over 30,000 schools that offer non-formal primary education; 70 per cent
of the pupils are girls.17
Recent analyses undertaken for the World Bank 18
reveal significant income-based differentials in child enrolment, and distinct regional
patterns of enrolment in poor populations. For example, in Latin America, there is near
universal enrolment of the poor in first grade but then substantial dropout grade by
grade, while in South Asia and Western and Central Africa the poor mostly do not enrol.
Differences between the rich and the poor in median years of schooling completed vary
considerably across countries, ranging from only one year to as many as 10. The effect of
adult income levels exceeds male-female differentials in many settings.19 Poor girls, however, suffer from a double
disadvantage that can severely restrict their opportunities.
Nearly one out of four adults in the world, around 1 billion people, cannot read, write
or do simple arithmetic.20
FIGURE 2: Educational Attainment by Gender, Region
Education leads to smaller, healthier families
One of the strongest and most consistent relationships in demography is between
mothers education and infant mortality the children of women with more years
of schooling are much more likely to survive infancy. 21
More-educated mothers have better health care, marry later and are significantly more
likely to use contraception to space their children. They have better skills for obtaining
and evaluating information on health care, disease prevention and nutrition. They also
have better access to resources, through earning opportunities and marriage, and can
manage them better. They are more likely to recognize the advantages of educating their
The relationship between womens education and fertility is also complex, but the
underlying pattern in most countries is that the more years of schooling a woman has, the
fewer children she is likely to have. In a small number of countries, particularly in
sub-Saharan Africa, fertility rises slightly with the first few years of womens
schooling, then falls with subsequent years of education. 22
In all recent studies, additional secondary education for women correlates with lower
Educated women are more likely to use
contraception and tend to marry later.
Educated women are more likely to use modern methods of contraception, and they tend to
marry later. Educated parents of both sexes also generally desire smaller families than
those with less education, and educated women tend to act on that reproductive preference
for fewer children. In other words, women with more schooling are more likely to have the
number of children they say they want.23
According to a study of Egyptian families, the educational aspirations that women and
men have for their children, particularly their daughters, are significant factors in how
many children they desire. Parents who hope for better education for their female children
tend to want smaller families, perhaps so that they can provide more fully for the
offspring they have.24
Women of all levels of education and economic status take steps to choose the number
and spacing of their children. Their ability to do so is a function of not only education,
but also circumstance, resources and custom.25
Population programmes help provide the means.
A gradual ageing of the global population in the decades to come is all but certain. The
reasons for this trend reflect the substantial human progress of this century
lowered infant and child mortality; better nutrition, education, health care and access to
family planning; and longer life expectancies.26
This transition is already well under way in the more-developed regions, where the
median age has risen from 29 in 1950 to 38 today and is projected to plateau at around 46
by 2050. In the less-developed regions, this process is just beginning; since 1950, the
median age has fluctuated between 19 and 24 (its current level). Africa, the worlds
most rapidly growing region, is also the youngest, with a median age of only 18. The
median age in all the less-developed regions is projected to begin a gradual rise to 37 by
There is every reason to believe that societies in both the more- and less-developed
regions can adjust to the higher median age of their inhabitants and the increasing ratio
of old to young people. Yet undoubtedly this new era will present distinct challenges. The
worlds people have never been this healthy or lived this long. In 1950, average life
expectancy globally was 46 years; in 2050 average life expectancy is projected to be 76,
and the median age is projected to be 38.
Countries in more-developed regions are already coming to grips with this unprecedented
transition and the issues that it presents with respect to the labour pool, care for the
elderly, and the potential for population decline.
Around the world, but particularly in the more-developed regions, countries with ageing
populations will face challenges pro-viding support and medical care for the elderly. The
percentage of young dependants will decline, but the proportion of older dependants will
The Youth Factor
Today, as a result of high fertility in the recent past, there are more young people than
ever over 1 billion between ages 15 and 24. They are entering their peak
childbearing years. In all developing countries, the proportion of the population aged
15-24 peaked around 1985 at 21 per cent. Between 1995 and 2050, it will decline from 19 to
14 per cent, but actual numbers will grow from 859 million to 1.06 billion.
These numbers ensure continued population growth, even if young people choose to have
smaller families than their parents had. Indeed, populations would continue to grow for
several decades even if "replacement-level" fertility were reached immediately.
This phenomenon, known as "population momentum", will account for up to two
thirds of the projected population growth worldwide, more in countries where fertility has
fallen most quickly. In Thailand, for instance, where three people out of ten are under
age 15, the population is projected to grow by 19 per cent between 1999 and 2025, even
though the average couple is having fewer than two children. Raising the average age at
which women have their first child from 18 to 23 would reduce population momentum by over
40 per cent.
Globally, lower birth rates create the strong possibility of a "demographic
bonus" in the less-developed regions in the next couple of decades, as a
"bulge" of young people grow up and become part of the work force while fewer
children are born. If enough employment opportunities can be created, these new workers
could well result in greater productivity and economic development, and generate
substantial revenues for health care, education and social security.27 There is every reason to believe that societies in
both the more- and less-developed regions will benefit from this change.
The Impact of AIDS
HIV/AIDS is now the leading cause of death in Africa and the fourth most common cause of
death worldwide.28 The Joint United Nations
Programme on HIV/AIDS (UNAIDS) estimates that 33.4 million people were HIV-positive as of
December 1998 and 2.5 million died of the disease in 1998 2 million in Africa. One
half of all new HIV infections are in young people between ages 15 and 24.
It is estimated that 95 per cent of those infected live in developing countries, and
two thirds live in sub-Saharan Africa, where 8.0 per cent of adults aged 15-49 are
HIV-positive. AIDS has a terrible effect on individuals and communities, as it strikes
down working people, orphans children, and places huge strains on health care and social
FIGURE 3: Regional Trends in Age Structure
the global scale, but it will have a devastating impact on several African countries.
Because of high fertility rates, most sub-Saharan African countries are still expected to
experience population growth, but for the most-afflicted nations the pace will be much
slower than it would be without the epidemic.29
Devastating Impact of HIV/AIDS in Africa
New estimates of the prevalence of HIV/AIDS indicate that the epidemic is more serious
than was previously thought. Estimates released in 1998 by UNAIDS and the World Health
Organization indicate that global HIV infections increased 10 per cent in 1998 to 33.4
million people worldwide. Last year alone, an estimated 5.8 million people contracted the
virus that causes AIDS.
Using UNAIDS estimates of the number of people currently infected, the United Nations
Population Division last year produced projections of future HIV prevalence rates and the
likely demographic impact in 34 of the most-affected countries (29 of them in Africa),
accounting for 85 per cent of currently infected persons and 91 per cent of all AIDS
deaths to date.
In the 29 African countries, the average life expectancy at birth is currently seven
years less than it would have been in the absence of AIDS. The average life expectancy in
the nine countries with an adult HIV prevalence of 10 per cent or more (Botswana, Kenya,
Malawi, Mozambique, Namibia, Rwanda, South Africa, Zambia and Zimbabwe) is estimated to be
48 years, 10 years less than it would have been in the absence of AIDS. However, the
population is not expected to decline in any of these countries.
In Botswana, with the worlds highest HIV/AIDS prevalence rates one of
every four adults is infected life expectancy has fallen from 61 years in the late
1980s to 47 today, and is expected to plunge to 38 by 20052010. Botswanas
population by 2015 may be 23 per cent smaller than it would have been in the absence of
AIDS. Nevertheless, because of continuing high fertility, the population is still expected
to nearly double between 1995 and 2050.
In Zimbabwe, the second-hardest-hit country, one in five adults is infected. Estimated
life expectancy at birth is 44 years and will fall to 41 in 20002005, 25 years less
than what would be expected in the absence of AIDS. Population growth has fallen to 1.4
per cent; it would be 2.4 per cent without AIDS. Zimbabwes population in 2015 is
expected to be 19 per cent lower than it would have been in the absence of the epidemic.
The Impact of AIDS in Sub-Sahran Africa:
Population Projections with and without AIDS
in the 29 most-afected Countries, 1980-2050
For a complete view of this chart,
please click here
In many countries, AIDS has erased decades of progress in reducing child mortality and
increasing life expectancy. In addition to increasing mortality, HIV/AIDS can also affect
demographic change by reducing the fertility of women who are infected and influencing age
at marriage, sexual behaviour and contraceptive use.
The course of this epidemic, both globally and in particular countries, is still to be
determined. There are some hopeful signs infection and mortality rates are falling
in a number of countries, though they are continuing to rise in others. The development of
the epidemic in South and East Asia, and particularly in India and China, is a particular
cause of concern.30 Slowing and stopping
the spread of AIDS will require improvements in comprehensive reproductive health care, as
well as better public education about the risks and consequences of HIV infection.
Prospects for Low-fertility Countries
An active debate is under way within the demographic community about the prospects for
future fertility in current (and projected) low-fertility countries. There may well be a
"bottom" for fertility rates for each society, a point after which rates will
begin to rise again, but demographers clearly cannot make that kind of prediction with any
One school of thought holds that below-replacement fertility is unlikely to persist
very long. In this view, projected fertility declines may be overstated because methods of
measuring current fertility rates do not capture completed fertility trends when more
younger women are delaying child-bearing until later in their lives.31 For instance, in the United States and
Sweden, the fertility rate dropped well below replacement in the 1970s and 1980s but rose
again to above 2.0 in the early 1990s. On the other hand, the fertility rate in Italy also
dropped below replacement in the late 1970s and has continued to fall, reaching 1.2 by the
It is considered significant that completed fertility among those who have any children
remains above the replacement level in most European countries. Statements of desired
fertility also remain at or above replacement level. Measured fertility declines might
stop when the age of marriage ceases to increase unless desired fertility falls.
Another school of thought holds that below-replacement fertility, particularly in
Europe, has become well-established and associated with continuing declines in desired
family size.32 It is not clear, meanwhile,
that all countries will reach below-replacement fertility. In some countries, fertility
declines have stalled at levels above replacement level.33
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