Scientists suggest they have found a reason why some shorter children perform less well at school.

University of Bristol researchers are linking low growth hormone levels with low IQ.

It is already known that low birth weight babies develop more slowly, reaching development milestones later and having slightly lower IQs than normal weight babies, according to a BBC report.

Short stature, according to the University report, is linked to poor post-natal growth and nutrition, is also known to be related to poorer performance in intellectual development tests and in educational achievement.

The Bristol team is working to establish what might happen in the body to explain these links, by focusing on insulin growth factor (IGF-I).