Major Causes of Death in the United States and Peru

* Primarily lower respiratory infections, including pneumonia.
Sources: National Center for Health Statistics, Leading Causes of Death, 1900-1998; World Health Organization, Causes of Death and Burden of Disease Estimates by Country, 2002; and National Center for Health Statistics, National Vital Statistics Reports 55, no. 19 (August 21, 2007).

Teachers Guide: Discussion guide

Question and Answer: Does AIDS have a significant impact on population growth?

Declining mortality, not rising fertility, has been the cause of the accelerating pace of world population growth. By attacking the causes of death that have kept population growth low for most of human existence, we have extended life expectancies and multiplied our numbers.

Life expectancy has increased steadily through history. During the Roman Empire, average life expectancy at birth was a brief 22 years. By the Middle Ages it had risen to about 33 years in England, and increased to 43 years by the middle of the 19th century. In the early 1900s, life expectancies in more developed countries ranged from 35 to 55. They have climbed to about 77 years today, and continue to improve. Meanwhile, life expectancy in less developed countries has gradually climbed, rising to about 65 years today.

Initial declines in mortality can be attributed to improvements in public health and living standards that accompanied the Industrial Revolution. Greater declines in the early 20th century were attributable to improvements in medical technology, which led to the control of such infectious diseases as smallpox and cholera. Further improvements in life expectancy are anticipated in most countries. In countries where death from infectious diseases is minimal, the improvements will come from the decline in mortality from degenerative diseases such as heart disease and cancer. However, in some countries, the spread of AIDS and other infectious ailments is a potential threat to further gains in life expectancy. In parts of Africa, where the spread of HIV infection is disproportionately high, life expectancy has been declining.

Causes of Death

The figure "Major Causes of Death in the United States and Peru" is useful for developing a better understanding of the changes in mortality in this century. It shows the major causes of death for the United States in 1900 and 2004, and for Peru in 2002. Each column accounts for all causes of death with the top causes specified. Some causes are combined because of their similarities. Data on cause of death should be interpreted cautiously because some causes are more easily identified than others and are reported more completely.

In the United States in 1900, pneumonia and influenza, tuberculosis, and diarrhea accounted for almost one-third of all deaths. Since then, mortality rates from these diseases have declined sharply. For example, pneumonia and influenza, which accounted for 12 percent of deaths in 1900 in the United States, accounted for 3percent in 2004. Heart disease and cancer, which account for half of all deaths today, caused only about 12 percent of deaths in 1900.

In Peru today, the causes of death are broadly dispersed. About half are attributable to the top four causes: cancer, respiratory infections, heart disease, and accidents. As Peru and other countries continue to develop, their causes of death may more closely resemble those of the United States today. As life expectancy improves and the role of infectious, parasitic, and respiratory infections further diminishes, more people will survive to older ages and chronic degenerative diseases such as stroke, cancer, and heart disease will make up a larger proportion of deaths.

Infant and Child Mortality

Deaths by Cause for Children Under Age 5 Worldwide, 2000-2003

* Deaths in the first 28 days of life.
Note: Numbers are rounded.
Source: World Health Oraganization, The World Health Report, 2005.

World Infant Mortality Rates in Selected Countries

Source: Carl Haub, 2007 World Population Data Sheet.

In less developed countries, the chances of dying are greatest at infancy and remain high during the first few years of childhood. A newborn child is fragile and has not developed immunities to common ailments. When a country has a high rate of infant death, it usually signals high mortality risk from infectious, parasitic, communicable, and other diseases associated with poor sanitary conditions and undernutrition. As a result, the infant mortality rate (IMR), or annual number of deaths of children under age 1 per 1,000 live births, is considered one of the most sensitive measures of a nation's health.

Worldwide, over 10 million children die annually before their fifth birthday. As the figure "Deaths by Cause for Children Under Age 5" indicates, about one-third of these deaths occur in the neonatal period (in the first 28 days of life). Neonatal causes include deaths from tetanus, severe infections, and premature births. Following neonatal causes, two of the primary causes of infant and child deaths are acute respiratory infections (such as pneumonia) and diarrhea. Other infectious diseases, such as malaria and measles, are also major causes of deaths to infants and children. Death from these conditions is almost unheard of for infants in more developed countries. However, in less developed countries where undernutrition is prevalent, medical facilities are scarce, and living areas may be unsanitary, infant deaths are common.

In 2007, world IMRs ranged from 2.4 per 1,000 births in Iceland to 166 per 1,000 births in Afghanistan, as shown in the figure "World Infant Mortality Rates in Selected Countries." As countries develop economically, infant mortality usually declines. The IMR in the United States was probably about 100 in 1900—around the level of the IMRs of some of the poorest countries in the world today. The IMR in the United States has now fallen to below 10. Many countries have even lower rates, with Iceland, Singapore, Japan, and Sweden heading the list.


Infant mortality rate (IMR): The annual number of deaths of infants under age 1 per 1,000 live births.

Less developed countries: Less developed countries include all countries in Africa, Asia (excluding Japan), and Latin America and the Caribbean, and the regions of Melanesia, Micronesia, and Polynesia.

Life expectancy: The average number of years a newborn infant can expect to live under current mortality levels. Most commonly cited as life expectancy at birth.

More developed countries: More developed countries include all countries in Europe, North America, Australia, New Zealand, and Japan.

Mortality: Deaths as a component of population change.