LONDON Bigger babies are smarter and develop into children who perform better at school than their smaller counterparts, scientists said.

A study of nearly 4,000 men and women born in 1946 showed that babies' weight at birth has an impact on their mental abilities and educational performance.

"It seems clear that birth weight has an influence on cognitive function," said Dr. Marcus Richards of Britain's Medical Research Council, a leading research charity.

"A baby who has not achieved full birth weight potential may also have not reached full brain development potential."

The researchers correlated with birth weight the results of tests that measured reading and arithmetic skills, nonverbal reasoning, memory, speed and concentration when participants were eight, 11, 15 and 26 years old.

Even after accounting for other factors such as father's social class, mother's education and birth order, which can influence cognitive function, there was a significant association between birth weight and cognitive development.

"There is evidence that factors such as maternal diet, alcohol use and smoking have an effect on birth weight, although the influence of these factors on cognitive development is unclear," added Richards, whose research is published in the ***British Medical Journal***.

The research was part of a larger study, the MRC national survey of health and development, that is concerned with health and its changes with age as well as the earlier life factors that affect health in middle age.

Low birth weight has also been linked to an increased risk of diabetes in middle and old age and is a risk factor for wheezing and lung disease later in life.

(Reuter)