How did life expectancy get to be so high in Japan and other industrial countries, and how much higher can it go? What are the prospects for Malawi and other developing countries to replicate this experience? Could unforeseen developments substantially alter prospects for rising life expectancy and falling mortality? The answers to these questions are the key to properly projecting mortality levels worldwide.

We will consider, first, trends in life expectancy over several centuries in industrial countries and over several decades in developing countries. Interpretation of these trends provides clues about how mortality should be projected. Next, we explain how projections have actually been made and assess their accuracy. Then we consider what likely future mortality trends should be reflected in projections. In summarizing the discussion, we also note some possible research directions to help improve projections.

Figure 5-1 shows how life expectancy has varied over the last 50 years across six major world regions. (Projections to 2050 are also shown and are considered below.) The magnitude of current variation (in 1990-1995) across regions is striking. Life expectancy ranges from 74 years in industrial countries to 49 years in Sub-Saharan Africa. The other developing regions—Latin America and the Caribbean, Asia, and the Middle East and North Africa—each have life expectancies between 66 and 70.

Industrial countries are experiencing the highest life expectancies ever observed. If mortality rates at all ages remain at current levels, more than half of the babies born this year in these countries will live to celebrate their 80th birthdays. Among baby girls, two-thirds will become octogenarians and half will reach age 85. Partly because these survival chances are much higher than the survival experienced by cohorts born 80 years ago, the oldest-old population (those age 80 and older) will grow substantially, even with no further improvements in mortality.

In contrast to life expectancy in industrial countries, life expectancy in developing regions is not only lower but also more variable. Across Sub-Saharan African countries, the highest and the lowest life expectancies are almost 40 years apart. This is because mortality is especially high in a few least-developed countries but close to industrial-country levels on some small islands. Although trends since 1950 suggest some narrowing of contrasts across regions, Sub-Saharan Africa remains an outlier.

As life expectancy varies across countries, age patterns of mortality also vary, in predictable ways. This is easiest to show from the change over time in one country. Figure 5-2 shows the risk of death at different ages among Swedish females between 1900 (when life expectancy was

Front Matter (R1-R20)

Executive Summary (1-14)

Introduction (15-36)

The Accuracy of Past Projections (37-52)

Transitional Fertility (53-82)

Posttransition Fertility (83-113)

Mortality (114-155)

International Migration (156-187)

The Uncertainty of Population Forecasts (188-217)

Biographical Sketches (218-224)

Index (225-236)

Appendix A: Computer Software Packages for Projecting Population (237-253)

Appendix B: Accuracy of Population Projections from the 1970s to the 1990s (254-302)

Appendix C: Predicting the Pace of Fertility Decline (303-314)

Appendix D: The Effect of Projection Error in Life Expectancy (315-317)

Appendix E: Simluating Migration Projections (318-325)

Appendix F: Estimating Expected Errors from Past Errors (326-348)