Premature babies have more than their share of health problems early in life and now a new study finds they also face an increased risk of premature death well into adulthood.

Premature babies are more common now than they were a few decades ago in the United States and many other countries, and medical advances mean that even very premature babies are more likely to survive. But does early birth have an impact on health when those babies grow up?

To find out, Stanford University researcher Dr Casey Crump and his colleagues used a database of 670,000 people born in Sweden in the 1970s.

"We found that people who were born preterm had a higher risk of dying in young adulthood than those who were born full-term". "And that risk of mortality increased the earlier in pregnancy that one was born."

Even a baby born just a couple of weeks early had an increased risk of death decades later.

That premature babies have a higher death rate in the first years of life is not surprising, but Crump says it had been thought that the risk decreased as the child got older.

"We found that that was true, at least in late childhood and adolescence. However, in young adulthood, an increased risk of mortality reemerged. And that was due to various causes, including respiratory and endocrine and heart disease - conditions that may have cumulative health effects that don't manifest until young adulthood."

A few years ago, a study published by the World Health Organization estimated that, globally, 10 percent of babies were born prematurely.

Crump says the findings of his study underscore the need to reduce the number of preterm births.

"It's extremely important for pregnant women to have regular prenatal care to reduce their risk of delivering preterm. And also, for survivors of preterm births to avoid other risk factors for disease, like smoking or obesity, in order to offset the increased risk that we found."

preterm: (of a baby) born prematurely 早产，早产婴儿

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（来源：VOA 编辑：张若琼）