A report on global adolescent health published in The Lancet revealed the U.S. has the highest teen mortality rate out the world's 27 wealthiest nations. Violent deaths among teens (including those caused by gang violence and homicide) are 10 to 20 times higher than other wealthy nations.

The report noted that while infant mortality is falling, wealthy nations are struggling to nurture healthy teens.

"The high-income world has been grappling with a rising tide of risks for non-communicable diseases, including the problems of obesity, physical inactivity, alcohol, tobacco and illicit drug use," the authors wrote.

Worldwide, the No. 1 killer of adolescents is suicide, with the highest rates in Belarus, Kazakhstan and the Russian Federation.