What Factors Affect Death Rates?


The rapid growth of the world's population over the past 100 years is not the result of a rise in the crude birth rate.

Instead, it has been caused largely by a decline in crude death rates, especially in developing countries.

Changes in crude birth and crude death rates for developed and developing countries, 1775-2002.



More people started living longer (and fewer infants died) because of:


Two useful indicators of overall health of people in a country or region are:


Some good news is that global life expectancy at birth:

Between 1900 and 2002, life expectancy in the US increased from 47 to 77 years and is projected to reach 81 years by 2025.


Some bad news is that in the world's 49 poorest countries, mainly in Africa, life expectancy is 55 years or less.

In many African countries life expectancy is expected to fall further because of increased deaths from AIDS.

Distribution of the 40 million people infected with HIV in 2001. Numbers in parentheses give the number of deaths from AIDS in 2001.


Because it reflects the general level of nutrition and health care, infant mortality probably the single most important measure of a society's quality of life.

A high infant mortality rate usually indicates:

World infant mortality rates in 2002.


Between 1965 and 2002, the world infant mortality rate dropped from:

This is an impressive achievement, but it still means that at least 8 million infants (most in developing countries) die of preventable causes during their first year of life.

Between 1900 and 2002, the US infant mortality rate declined from 165 to 6.8.

This sharp decline was a major factor in the marked increase in US average life expectancy during this period.

Despite this improvement, 37 countries had lower infant mortality rates than the US in 2002.

Three factors keeping the infant mortality rate higher than it could be:

  • inadequate health care for poor women during pregnancy and for their babies after birth

  • drug addiction among pregnant women

  • the high birth rate among teenagers

The good news is that the US birth rate among girls ages 15-19 in 2002 was lower than at any other time since 1940.

Some bad news is that the US has the highest teenage pregnancy rate of any industrialized country.

Each year about 872,000 teenage girls become pregnant in the US (78% of them unplanned) and about 253,000 of them have abortions.

Babies born to teenagers are more likely to have low birth weights, the most important factor in infant deaths.