A new study by the researchers at Stanford University finds that premature babies, when grow up to be young adults, could face slightly increased death rates.

 This is an entirely new finding, said Casey Crump, lead author of the study.

 Even people born just a couple of weeks early had an increased risk of mortality, he said.

Health problems are common among premature babies, who also are more likely to die during early childhood and young adulthood than their full-term born peers.

Premature babies are more prone to problems like heart disease, diabetes and asthma.

Crump's team followed a group of nearly 6,75,000 babies born in Sweden between 1973 and 1979.

They found that children born before 37 weeks of pregnancy were much more likely to die before age five than others.

The pattern disappeared in late childhood and adolescence, but then re-emerged in early adulthood -- from 18 to 36 years.

According to Reuters, the report states that nearly 12 to 13 per cent of the babies born in the U.S. are preterm, and the rate of survival has risen fast over the past few decades.

It found out that the young adults born in between six to seven months of pregnancy, the death rate was 0.94 per 1,000 people per year.

For those born at nine to 10 months, considered full-term, the rate was 0.46 per 1,000.

According to Crump, between 12 and 13 percent of babies in the U.S. are now born preterm, and the rate of survival has risen fast over the past few decades.

The findings of the study are published in the journal of the American Medical Association.