Have preterm births peaked?

Preterm births in the United States went up steadily from 1981 to 2006, but now they seem to be going back down, according to a new report from the National Center for Health Statistics in Hyattsville, Md.

This is the first two-year downturn in nearly three decades, the report states.

The peak year for preterm births was 2006, when they accounted for 12.8 percent of all births. The rate in 2008 was 12.3 percent.

A preterm birth is one that occurs before 37 weeks of gestation. Babies born before this point are more likely to have serious health problems compared with infants born later in pregnancy. Even babies just shy of 37 weeks are more likely to have "neurodevelopmental problems," or to die before they turn one year old, than are babies born at term, the report states.

Preterm rates appear to be falling among women of all age groups younger than 40, among all ethnic groups, in all types of deliveries and in most parts the country. Several states saw a flat rate of preterm births over the last two years, but only Hawaii experienced an increase. The decrease was similar for singleton and multiple births.

However, the report notes that "the U.S. preterm birth rate remains higher than in any year from 1981 to 2002, with large differences still evident by race and Hispanic origin. Further research is necessary to explain the factors behind the current downturn and to develop approaches to help ensure its continued decline."