March of Dimes' annual report on infant and maternal health drops the U.S. from a C- to a D+, citing a 15-year high in the preterm birth rate. But it also offers some encouraging signs and solutions.

A report from the nonprofit March of Dimes finds that 36% of counties in the U.S. are "maternity care deserts," meaning they have no obstetric hospitals or birth centers and no obstetric providers.

Leaders with the March of Dimes and the Robert Wood Johnson Foundation say the United States is the most dangerous developed nation in which to give birth, especially for Black women.

This isn't the first big vaccine rollout, and the past holds lessons for the pandemic present. Here's a look at how the polio vaccine overcame U.S. hesitancy.