Babies who are born with a low birth weight face an increased risk of death right up until they are teenagers, a new study has found.

Welsh researchers analysed over 12 million births that took place between 1993 and 2011. During this time, almost 75,000 children under the age of 18 years died. While most of these deaths occurred during the first year of life, almost one in four occurred between the ages of one and 18 years.

The study found that death rates were higher among those who had a low birth weight. Among those with a very low birth weight - under 2,500g (5.5lbs) - death rates were 130 times higher compared to those with a normal birth weight.

These results applied to both age groups - those under one and those aged one to 18.

As expected, events around the birth, including being born prematurely, had a key role to play when it came to the death of infants. There tended to be more causes of death for older children, including respiratory conditions, cancer and accidental deaths.

"We know low birth weight is associated with increased mortality rates in infancy. However, its association with mortality in later childhood and adolescence is less clear cut. This study is significant as it shows, for the first time, that low birth weight is associated with increased death rates from infancy right through to adolescence," explained lead researcher, Prof Sailesh Kotecha of Cardiff University.

The researchers believe that targeting risk factors known to contribute to low birth weight could help reduce such deaths.

"The study reaffirms the need to tackle important factors such as maternal smoking and deprivation which are well known to contribute to low birth weight. By better understanding and ameliorating influences that lead to low birth weight, deaths in infancy and beyond could be cut," Prof Kotecha said.

Details of these findings are published in the journal, PLOS Medicine.