Take that, Ireland. The United States’ infant mortality rate dropped 12 percent from 2005 through 2011, a steady decline that researchers say may be due in part to fewer premature births. The dip is welcome news after rates leveled off from 2000 to 2005, according to a report released Wednesday by the Centers for Disease Control and Prevention. Some of the most surprising improvements were in Southern states—Georgia, Louisiana, North Carolnina, and South Carolina—which have long been plagued with higher infant mortality rates than the rest of the country’s. The rate dropped by more than 20 percent from 2005 to 2010 in all four states.