Preterm Birth Rates for 100 US Cities (IMAGE) March of Dimes Foundation Caption Portland's preterm birth rate was 7.2 percent, earning that city an "A" on the report card and Shreveport got an "F" for its 18.8 percent rate in 2013, the most recent year statistics were available for large cities. In addition to Portland, Oxnard, California; St. Paul, Minnesota; and Seattle, Washington are the only other cities that earned "As" on the national report card. Credit March of Dimes Usage Restrictions Please credit the March of Dimes License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.