Pakistan is riskiest country for newborns: Unicef

Still, among countries that have made dramatic improvements is low-income Rwanda, which more than halved its rate from 1990 to 2016, illustrating that "political will to invest in strong health systems... is critical," the report said.

Education matters, too. Babies born to mothers with no education face nearly twice the risk of early death as babies whose mothers have at least a secondary education.

The United States - generally affluent, but with considerable income inequality and wide variations in access to health care - was only the 41st safest country for newborns.

The countries with the lowest newborn mortality rates, after Japan, are mostly well-off countries with strong education and health care systems:

Iceland (a one in 1,000 chance of death)

Singapore (one in 909)

Finland (one in 833)

Estonia and Slovenia (both one in 769)

Cyprus (one in 714)

Belarus, Luxembourg, Norway and South Korea (all with risks of one in 667).