State health officials say Alabama's infant mortality rate increased last year to its highest rate in four years.
Officials said Wednesday that there were 8.9 infant deaths for every 1,000 births last year. That means more than 500 children didn't live to their first birthday.
The 2012 statistic was a marked increase from 2011, when the rate was 8.1 - the lowest in state history.
Officials say they're puzzled by the increase, which happened despite decreases in the state's teen birth rate and a drop in the proportion of premature babies.
Alabama traditionally has a high rate. The most recent data say the national infant mortality rate was 6.05 in 2011.
The state's rate tends to vary. It was 9.5 in 2008, 8.2 in 2009, and 8.7 in 2010.