Has the percentage of preterm births (an important risk factor for infant mortality) increased from 2000 to 2005?
Preterm birth (births at less than 37 completed weeks of gestation) is a key risk factor for infant death. The percentage of preterm births has increased rapidly in the United States in recent years. From 2000 to 2005, the percentage of preterm births increased from 11.6% to 12.7%-a 9% increase. From 2000 to 2005, increases occurred for each preterm gestational age grouping. For example, the percentage of very preterm births (less than 32 weeks of gestation) increased by 5%-from 1.93% in 2000 to 2.03% in 2005. From 2000 to 2005, the increase was most rapid for infants born in the late preterm period (34-36 weeks of gestation). The percentage of late preterm births increased by 11%-from 8.2% in 2000 to 9.1% in 2005. The overall percentage of preterm births has increased in the United States since the mid-1980s. Although a portion of the increase is due to increases in multiple births, the percentage of preterm births also increased among single births (6).
