The March of Dimes has given Louisiana and Mississippi grades of F for high premature birth rates.
The group says 15.3 percent of all babies born in Louisiana last year spent less than 37 weeks in the womb. In Mississippi, that rate was 17.1 percent.
Alabama and Puerto Rico got the only other Fs, for rates of at least 14.6 percent.
Mississippi health department spokeswoman Liz Sharlot said nobody was available for comment Friday.
Louisiana health secretary Kathy Kliebert says Louisiana has a long way to go. But she says a campaign that started in late 2010 to reduce the premature birth rate is working.
Louisiana's rate went from 15.1 percent in 2010 to 15.6 in 2011, but fell three-tenths of a percentage point last year.
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