Improvements in child and maternal health care have saved the lives of some 90 million children around the world since 1990. According to the United Nations' Children's Fund (UNICEF), the number of children under the age of five dying of preventable causes each year has plummeted from 12.6 million in 1990 to 6.6 million in 2012 -- a reduction of nearly fifty percent.

The Pulitzer Center on Crisis Reporting documented this extraordinary achievement in an interactive world map tracking country's mortality rates for children under five using UNICEF data.

In Bangladesh, for example, child mortality rates declined by 72 percent between 1990 and 2012, partly due to better immunization programs and treatment of diarrhea and vitamin deficiencies. Around the globe, economic development and investment in healthcare have improved children's chances of surviving their fifth birthday, the Pulitzer Center notes.

Yet momentous challenges remain. Nearly half of infant deaths around the world are connected to under-nutrition. And UNICEF warns that some 35 million children will die preventable deaths between 2015 and 2028 if child mortality doesn't decline faster.