Fact number one.
Life expectancy increases very rapidly as GDP
per capita increases, and then levels off.
This is one of the most robust findings from
a careful study of status quo conditions and historical experiences.
But note that why this leveling off in life
expectancy occurs in middle income countries is not intuitively obvious.
You could tell an equally plausible story that life expectancy would grow
slowly while a public health infrastructure
platform was being put in place.
And then, when everything was completed, life expectancy would then take off.
In the transition from low-income to
middle-income status, countries undergo many changes simultaneously.
Life expectancy rises, rural households migrate
to cities, water and sanitation conditions improve,
family size declines with the demographic
transition, diet improves and housing conditions improves.
It is very difficult to tease out the cause
and effect relationships because everything is changing at once.
The public health revolution that caused this increase in life expectancy is
in large part due to improved
water and sanitation, diet, vaccines and antibiotics.
But remember we need financing.
You need economic growth to finance piped
water and sewer networks and other health interventions.
Fact number two, childhood mortality rates are
declining and the rate of decline is accelerating.
This is great news.
Not only are things getting better, they're getting better faster.
The global decline from 1990 to 2010 was 2.1% per year for neonatal mortality,
2.3% for post neonatal mortality, and 2.2% for childhood mortality.