ST. PAUL, Minn. — Minnesota’s rate of pre-term births edged up slightly in the past year, in contrast to the declines seen in most other states.

A report from the March of Dimes showed 33 states had their premature birthrate drop, Minnesota Public Radio News reported Friday (http://bit.ly/1aNWLRR ).

Minnesota’s rate was 10.2 percent in 2012, up from 9.9 percent in 2011. March of Dimes officials in the Minneapolis area said they hope the rise is just a blip, and said Minnesota gets a good mark overall; the state has received a “B” from the organization for seven years in a row. The national rate is 11.5 percent.

Danielle Prenevost, a spokeswoman for the Minnesota chapter of March of Dimes, called it a disappointment.

“We really did expect to do better,” she said.

Minnesota has significant disparities in preterm birth rates between whites and minorities — among the widest gaps in the nation.

State health commissioner Ed Ehlinger said rapid demographic changes in the state are showing up in the preterm birth rate.

Among Minnesota’s American Indians, 13 percent of babies are born prematurely. The rate is 12.7 for black infants, compared to 9.4 for whites.

“It’s really a math problem,” Ehlinger said. “As we get an increasingly diverse community with persistent disparities our rates are not going to improve as rapidly as they should.”

The March of Dimes report showed improvements in Minnesota in two key health areas in the past year: the rate of uninsured women and the percentage of women who smoke.