United States - Infant Mortality Rate for Least Developed Countries was 39.66168 Number per 1,000 Live Births in January of 2023, according to the United States Federal Reserve. Historically, United States - Infant Mortality Rate for Least Developed Countries reached a record high of 160.79593 in January of 1966 and a record low of 39.66168 in January of 2023. Trading Economics provides the current actual value, an historical data chart and related indicators for United States - Infant Mortality Rate for Least Developed Countries - last updated from the United States Federal Reserve on September of 2025.