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population pressures > features > defusing the population bomb

Defusing the population bomb

Posted: 16 Jan 2007

by Carl Haub

World population reached 6 billion in 1999, 6.5 billion in 2006 and is expected to top 7 billion in 2012. The key factor in this growth is the number of babies born to each mother. Replacement level is 2.1. Forty years ago women in the developing world were having triple that number, and a population explosion loomed. So where are we today? We asked the eminent demographer, Carl Haub, to provide the answer.

Back in the 1960s, awareness that something unheard of was happening in world population growth began to spread. The world’s developing countries had entered a period of rapid population growth rather than suffer devastating famines as had often been feared.

This sudden spurt resulted from rapidly improving health conditions at a rate that the industrialised countries of Europe and North America had never experienced. Public health measures that had taken centuries to develop in the world’s rich countries spread almost overnight, it seemed, to the developing countries of Africa, Asia, and Latin America. As a result death rates fell, although the picture certainly improved faster in some areas than in others. Death rates fell but birth rates did not. High birth rates were a hallmark of rural, traditional societies and those societies were slow to change.

As a result, population growth rates increased to three per cent per year or more. A three per cent annual growth rate will double a population in size in only 23 years. The population “bomb,” as it came to be known, was in full swing.

Looking back to the 1960s, the demographic events that have taken place since that time is truly remarkable. In the 1960s, family planning was virtually unknown in developing countries, few rapid growth countries had any policies to slow growth, and it is doubtful that societies were prepared for the notion of limiting the number of one’s children. In the past, high infant and child mortality, as well as the still-persistent desire for sons, meant that couples produced large numbers of children, six to eight each. Thus, the size of successive generations tripled in size or even more.

Six children

But countries did begin to at least recognize that a demographic phenomenon was taking place within their borders and some began to address the often-delicate issue of family planning. India was the first, announcing the beginning of what was to an effective and, at times, series of population policies and activities in 1952.

In the 1960s, women in developing countries were averaging six children each. Today, that figure has been halved. The astonishing speed with which this occurred is often lost in discussions today. Many developing countries achieved in mere decades what had previously taken the developed countries centuries. And, much of the fertility decline has been achieved in poor, rural areas although the story is somewhat different from place to place.

TFR barchart

Why is fertility important? The future trend in the birth rate is the single most important determinant of future population size even with the global impact of HIV/AIDS. Global population projections that we all use, such as those of the United Nations Population Division, assume that, not only will fertility decline everywhere, but that it will decline to below two children per woman in the developing countries. Thus, when we quote the UN to say that “world population will rise to 9.1 billion” in 2050, we should at least be aware of the hundreds of assumptions that must come true to realise that figure. Future fertility trends will play the key role.

Currently, the regional situation and prospects for further decline is as follows:


Africa may rightly be considered the last to join the contemporary transition to lower birth rates. While there has been some decline, from a total fertility rate (TFR)* of 6.9 in the 1960s to about 5.1 at present, most of that has been in the continent’s extreme north and south.

Much of the reason for the slow decline may be traced to comparatively weak national population policies in many countries but also to a clearly persistent desire throughout Africa for larger families. In Burkina Faso, for example, women stated that their ideal number of children was 5.6 in a 2003 Demographic and Health Survey while men gave 6.3. Even the younger generation said that their ideal number was 4.9 and 5.6, respectively. One disturbing trend that has been noted in a number of surveys is a trend to a “slowdown” in fertility decline in countries which had previously been somewhat successful such as Cameroon, Ghana, and Kenya.


In Asia, fertility has, on the one hand, declined to the lowest of the developing regions but it is also the region with the widest variation in levels, from an astoundingly low 1.1 children per woman in South Korea and Taiwan (both considered “NICS,” or newly-industrialized countries) to values as high as 6.8 in Afghanistan to 6.2 in Yemen. Currently, Asia’s TFR stands at 2.4 children per woman, although it is 2.8 when the effect of China’s very low fertility, driven by its “one child” policy is removed.

Generally, fertility tends to decline as one moves from west to east in Asia, from the Middle East to the Pacific. In the eastern sector, economies are somewhat more advanced and family planning programmes have been well administered, such as in Indonesia and Thailand. A major question mark is India, whose TFR at slightly below three children per woman masks wide variation within the country. Higher fertility in northern states, states which happen to have large populations and high levels of illiteracy, may cause much higher population growth than is generally expected, particularly if fertility decline in those states is slower than it was in the better-educated south.

Latin America/Caribbean

Overall, the TFR in this region, 2.5, is close to that of Asia but there is also less variation across countries. Only two countries have TFRs above four children per woman, Guatemala and Haiti. In the region’s largest country, Brazil, the TFR is now about 2.3, a low rate that can be attributed to considerable economic development and urbanisation.

In Latin America, fertility decline has one difference, the apparent resistance of the TFR to decline to two children or less as it did in a number of Asian countries. Thus, a country such as Argentina, which has had quite low fertility for decades, has never had a TFR actually approach the replacement level of 2.1. This is sometimes referred to as the “Latin American exception.”

Industrialised countries

As fertility decreased in the developing world, a parallel decrease has taken place among the industrialised countries, albeit with very surprising consequences. No one anticipated TFR’s as low as 1.2 or 1.3 and the population decline and ageing that accompany such low fertility.

While such low fertility was at first more prevalent in Northern and Western Europe, the breakup of the Soviet Union in 1991 resulted in steep fertility declines in both its former republics and its eastern European satellites. As a result, some of the lowest fertility is to be found in those countries.

Europe is not alone in this situation, as Japan, Canada, and other East Asian countries have joined them. One exception to this low fertility pattern is the United States, whose TFR of 2.0 is partly due to the higher fertility of immigrants, but also to that of the traditional majority population, white non-Hispanics, whose fertility is only slightly less than the national average. Today, European countries and others, such as Japan and South Korea, are addressing their low fertility as a national crisis and are introducing measures to ease the burden of childbearing on couples in contemporary, two-earner societies.

Uncertain future

Global fertility patterns have changed remarkably in the past 40 years and have been full of surprises. Doubtless, the future will provide its own twists and turns and the size of future world population hangs in the balance.

Much will depend upon the political will to persevere with the agenda agreed by the world's governments in Cairo 12 years ago to extend reproductive health and family planning services and to educate girls and promote opportunities for them. In a world threatened by climate change, spreading deserts and water shortages, the quicker population stabilises the better.

Carl Haub holds the Conrad Taeuber Chair of Population Information
Population Reference Bureau

*NOTES:The most meaningful way in which fertility levels can be described is the use of the total fertility rate, the average number of children a woman would have in her lifetime if the rate of childbearing of a particular year were to remain constant.

How do we know the level of fertility worldwide, particularly since almost no developing country records or registers births and deaths? In additional to census data which do provide a basis to estimate birth and death rate, a most valuable source of information is a series of demographic surveys that has been in existence since the mid-1970s. Today, we have the Demographic and Health Surveys, the Reproductive Health Surveys and a number of regional survey programmes. These supply more detailed data than censuses can and are taken at more frequent intervals. While no survey taken under often arduous conditions in developing countries can claim to be perfect, we would know far less without them..

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