In 2005, the United States ranked 30th in the world in infant mortality. Infant mortality rates for preterm (<37 weeks of gestation) infants are lower in the United States than in most European countries; however, infant mortality rates for infants born at 37 or more weeks of gestation are higher in the United States than in most European countries. One in 8 births in the United States were preterm in 2005, compared with 1 in 18 births in Ireland and Finland, and 1 in 16 in France and Sweden. If the United States had Sweden's distribution of births by gestational age, nearly 8,000 infant deaths in the United States would be averted each year, and the U.S. infant mortality rate would be one-third lower. The main cause of the United States' high infant mortality rate when compared with Europe is the very high percentage of preterm births in the United States, the period when infant mortality is greatest.