Births at 32-36 weeks account for more infant deaths than earlier births.

An examination of population-based data from the US and Canada revealed that infants born at 32-36 weeks gestation account for more infant deaths than earlier births. For the 1995 US birth cohort and the Canadian infants born in 1992-94 preterm births account for 9% and 13% of infant deaths respectively. In both cohorts these infants accounted for a higher proportion of deaths before the age of 1 year. Further analyses revealed that mildly preterm infants were 3 times more likely as those born at term to die within a year; moderately preterm infants were 6.6 times more likely as full-term babies to die at the age of 1 year. Relative risks of death for these infants were higher in the neonatal period than for the remainder of the year. The common causes of death were asphyxia infection sudden infant death syndrome and external causes. The researchers point out that while most studies of mortality among preterm infants focus on births that occurred at <32 weeks gestation births at 32-36 weeks are much more common and have an important public health impact.