The researchers at Duke University gathered their findings from an experiment involving 1.16 million births in Norway between 1967 and 1988. Of this number, 5.2 percent, or 60,354, were deemed to be premature births, being born up to 37 of the 40 normal weeks after conception.
The AFP reported that of all the premature boys, those born after 22 to 27 weeks after conception were discovered with a 1.33 percent mortality rate between the ages of 1 and 5.9. The rate drops to 1.1 between the ages of 6 and 12.9 years.
Compared to babies born full term, the findings show that the babies are at a risk 5.3 to seven times higher.
For those born between 28 and 32 weeks, the mortality rate was .73 percent for the younger group, and .37 for the older group.
For the premature girls, ages one to 5.9 years have a 1.71 mortality rate, or almost 10 times higher than normal baby girls.
The scientists found no deaths among those between six and 12.9 years old.
In terms of fertility rates, both male and female born 22 to 27 weeks after conception had reproduction rates of 13.9, and 25 percent, respectively. Those born between 28 and 32 weeks showed 38.6, and 59.2 percent.
USA Today reported that the scientists also found premature children to be less likely to graduate high school.
Also, premature women are at a greater risk of producing premature babies themselves. These babies, however, show up with a higher death rate during the first year.
"Prematurity is a very significant health problem that lasts a lifetime," commented David Adamkin of the American Academy of Pediatrics.
