The health-care implications of being born premature are much broader and reach further into adulthood than previously thought, according to a long-term study of more than one million men and women by researchers from Duke and the University of Bergen in Norway.
In an article published in the Journal of the American Medical Association, the researchers say their data show that preterm birth contributes to several long-term health and quality-of-life issues, including lower educational achievement, lower rates of reproduction, and an increase in the likelihood that future offspring will be born preterm and with complications.
Preterm birth, defined as birth before thirty-seven weeks of gestation, is the leading cause of infant mortality. Research has documented the short-term complications as well as the long-term disabilities survivors must cope with.
"When a baby is born preterm, we tend to focus on the short-term risk of complications," says Geeta Swamy, an assistant professor of maternal and fetal medicine at Duke and lead author of the study. "While it is true that the risk of complications is highest in the immediate time period including hospitalization and the first year of life, that risk continues into adolescence. And the earlier you're born, the higher the risk."
Working with colleagues at the Norwegian Institute of Public Health, Swamy and fellow researchers at Duke used a national population-based registry containing birth and death data to analyze how preterm birth affects long-term survival, subsequent reproduction, and next-generation preterm birth. The population studied spanned twenty years, from 1967 through 1988. Births occurred between twenty-two weeks and thirty-seven weeks gestation.
The study found, among other things, that boys born between twenty-two and twenty-seven weeks had the highest rate of early childhood death; reproduction rates were considerably lower for men and women born preterm when compared with those born at term, with rates increasing in direct proportion to higher gestational age; women born preterm were more likely to experience recurrent preterm birth and an increased risk of adverse outcomes in their offspring; and that the lower the gestational age, the greater the risk of having less education.
Swamy says that the study indicates that gestational age plays a very large role in overall health. She argues that gestational age may even be a stronger predictor of how well a baby will do than low birth weight.