The study, conducted using Norwegian birth data, raises questions about future risks for even tinier babies saved today by modern medicine. Previous studies have shown that premature infants faced many neurological and developmental problems, but the new findings to be reported Wednesday indicate that the problems persist throughout the child's lifetime.
"Are we improving their survival but at the expense of significant problems down the road?" asked study leader Dr. Geeta Swamy of Duke University Medical Center.
One in eight American infants is now born prematurely, a total of more than half a million per year. A full term pregnancy is defined as 38 weeks or longer. Premature birth are attributed to growing incidence of assisted reproduction, which often produces twins or triplets, which are more likely to be born prematurely.
There is also a rising incidence of elective Cesarean sections leading to premature births. Babies born prior to 37 weeks suffer from learning disabilities, neurological problems, lung diseases and cerebral palsy.
The researchers studied 1,167,506 singleton births in Norway between 1967 and 1988, following the children through 2002 and analyzed their educational achievement and reproduction in the group born between 1967 and 1976. A total of 5.2 percent of the births were premature, less than half the percentage in the U.S.
For boys born the most prematurely, between 22 and 27 weeks, their risk of death was 5.3 times normal between the ages of 1 and 6 and seven times normal between 7 and 13. For boys born between 28 and 32 weeks, the risk of death was 2.5 time normal in early childhood and 2.3 times normal in late childhood.
The most premature girls had 9.7 times the normal risk of death between ages 1 and 6, but no increased risk between 7 and 13. Girls born between 28 and 32 weeks did not have a significantly increased risk of death.
The research concluded that boys born the most prematurely were 76 percent less likely to reproduce, with only about one in seven having children. Women were 67 percent less likely to reproduce, with one in four having children.
The study, appearing in Wednesday's Journal of the American Medical Association, says women who were preemies had a higher risk of giving birth to premature babies themselves. The reason could be attributed to genetic differences, birth defects, economic factors and social obstacles.
