The Great Health Improvement

How life expectancy and child survival improved dramatically across the world over the past century, and what drove the change.

One of the greatest achievements in human history has happened within living memory: people almost everywhere are living much longer, healthier lives.

The numbers

Around 1900, global life expectancy was estimated at about 32 years.
Today it is over 70 years.
The number of children dying before age five fell from about 12.8 million in 1990 to under 5 million in recent years, even though the world’s population grew.
India’s life expectancy rose from about 32 years at independence to around 70 today.

What drove the improvement?

Economists and historians point to several factors:

Clean water and sanitation, which reduced diarrhoeal diseases.
Vaccines, which prevented measles, polio, diphtheria and other killers. Smallpox was eradicated in 1980.
Antibiotics and other medicines.
Better nutrition as incomes and food production rose.
Education, especially of mothers, which improved child care and health practices.
Simple, cheap treatments, such as oral rehydration salts for diarrhoea.

Not just income

The economist Samuel Preston showed in 1975 that at any given level of income, life expectancy rose over time. This means health improved not only because countries got richer, but because knowledge and technology spread, making health cheaper to achieve.

Remaining gaps

Life expectancy in the poorest countries is still well below that in rich countries.
Many child deaths are still caused by preventable conditions such as pneumonia, diarrhoea and malaria.
Non-communicable diseases, such as heart disease and diabetes, are rising in low- and middle-income countries.

The economics

Economists study which investments save the most lives at the lowest cost, how to finance health systems, and how health affects economic growth. This module explores these questions.

Three generations

A grandmother in rural India lost two of her six children in infancy. Her daughter had three children, all of whom survived after being vaccinated and born in a health centre. Her granddaughter expects to live into her late 70s. Within three generations, health prospects changed enormously.

Thinking health improves only when countries get rich

Spreading knowledge, vaccines and cheap treatments has improved health even in poor countries. Health at a given income has risen over time.

Key takeaways

Global life expectancy rose from about 32 years in 1900 to over 70 today.
Child deaths fell from about 12.8 million in 1990 to under 5 million.
Water, vaccines, medicines, nutrition and education drove the change.
Samuel Preston showed health improved at every income level over time.