LONDON - How much babies weigh at birth is an important factor in their physical and mental development and even influences how well they do in exams later in life, British researchers said recently.

Small babies begin life at a disadvantage because medical studies have shown that their tiny size increases their risk of developing diabetes, asthma, respiratory problems and heart disease as they grow older.

Researchers at the University of Liverpool in England have also shown that teenagers who were very small babies do not score as high on national educational tests as adolescents who had been bigger at birth.

"The very low birth-weight children don't perform as well in our GCSE exams as their matched comparison group," said Professor Peter Pharoah, referring to the General Certificate of Secondary Education tests given to 16-year-old British students.

When he and his colleagues compared the exam results of 167 matched pairs of children they found that students who had weighed less than 1,500 grams at birth scored, on average, half a grade lower on each subject than pupils who had been bigger babies.

The researchers ruled out education and social factors because the children were in the same school and came from similar backgrounds. Low birth-weight, which results from premature delivery or slow growth in the womb, seemed to be the major factor.

"We don't know to what extent this difference in performance is because they haven't grown well or because they are born prematurely," said Pharoah, who reported his findings in the journal Archives of Disease in Childhood.

The researchers have been studying the children since they were born. They tested them at eight years old and found the low birth-weight youngsters had lower IQs and did not perform as well in reading and motor skills as the other children.

"There is something happening in these low birth-weight children," possibly before birth or shortly afterwards, said Pharoah.

"Most of these children are surviving with improved care but we need to be thinking of what else we need to do to give them the best start in life," he added.

(Agencies via Xinhua)