After a century of declines, the U.S. infant mortality rate barely budged between 2000 and 2005, causing the United States to slip further behind other developed countries despite spending more on healthcare, according to a report released Wednesday. The rate was 6.86 infant deaths per 1,000 live births in 2005, virtually unchanged from 6.89 in 2000. In 1900, the rate was 100 deaths per 1,000 live births. The United States dropped to 29th in the world in infant mortality in 2004, the latest year for which data are available from all countries, tying with Poland and Slovakia. The year before, it was 27th. In 1960, it was 12th. The report from the Centers for Disease Control and Prevention attributed the leveling off in mortality to a 9% increase in premature births over the same period and to stalled progress in saving the earliest preterm infants. Premature birth and low birth weight are by far the biggest causes of infant death. Infant mortality rates vary by race and ethnicity, from a high of 13.63 per 1,000 births for African American women to a low of 4.42 for Cuban Americans, according to the CDC report. Differences in socioeconomic status and access to medical care did not entirely explain the gap, the report said. Premature births are increasing, possibly tied to rising rates of obesity, diabetes and hypertension. What those conditions have in common is that they are preventable, and that ... is where the United States falls behind other developed countries.