Why is the infant mortality rate in Cuba lower than in the United States?

I’ve got my own hypothesis for this remarkable fact, but before sharing this I’d first like to hear and understand your viewpoints. The following numbers are from CIA World Factbook (2009 estimates).

The infant mortality rate is the number of deaths of infants under one year old in a given year per 1,000 live births in the same year. Here are a few examples:

Japan – 2.79
Germany – 3.99
Cuba – 5.82
United States – 6.26
Poland – 6.80
Russia – 10.56
China – 20.25
India – 30.15
Ghana – 51.09
Sudan – 82.43
Afghanistan – 151.95

http://en.wikipedia.org/wiki/List_of_countries_by_infant_mortality_rate