In a bit of good news, a United Nations report released last week finds that the global childhood mortality rate — the number of children who die before age 5 — has declined by 47 percent since 1990, from 90 out of 1,000 live births to 48.

The bad news is that the world appears likely to fall short of the Millennium Development Goal, adopted in 1990, of reducing childhood mortality by two-thirds by 2015.

Childhood mortality is now increasingly geographically concentrated, with sub-Saharan Africa accounting for nearly half of the world's deaths before age 5. This region plus South Asia account for more than 80 percent of them.

Mortality declined by only 45 percent in this region. Just two countries — India and Nigeria — account for more than a third of these deaths. East Asia saw the most progress — driven largely by China — with a 74 percent decline.

Childhood mortality is one of the starkest divides between rich and poor countries, with the entire developed world accounting for just 1.4 percent of under-5 deaths.

Looking at the globe as one country, the world might soon be an upper-income country. But its infant mortality rate is still slightly worse than South Africa's.

JOSHUA KEATING, Slate