As of 2017, the countries with the highest infant mortality rates included Afghanistan, Somalia, the Central African Republic, and Guinea-Bissau. The countries with the lowest infant mortality rates included Japan, Iceland, Singapore, and Norway. As seen in many other developed countries, the infant mortality rate in the United States has steadily decreased over the past few decades. From 1990 to 2017, the infant mortality rate in the U.S. decreased from 9.4 to 5.6 deaths per 1,000 live births, yet this is still higher than that of comparable countries. Within the United States, the state with the highest infant mortality rate is Mississippi, with a rate of 8.9, compared to a rate of just 3.9 in New Hampshire, the lowest of any U.S. state.
Disparities in infant mortality rates are not only found on a state level in the United States but are also seen based on urbanization and by ethnicity. In general, the infant mortality rate in rural counties is higher than that of large urban counties. Moreover, there are differences in the causes of infant mortality depending on urbanization. Infant mortality caused by congenital malformations, sudden infant death syndrome, and unintentional injuries are more common in rural counties, while low birthweight and maternal complications play a larger role in infant deaths in large urban counties. An even larger disparity in infant mortality can be found based on ethnicity. In 2017, the infant mortality rate among non-Hispanic black women was 10.97, while the rate among non-Hispanic white women was only 4.67 deaths per 1,000 live births.