Family affluence is key to achievement

The affluence of a child's upbringing has a greater bearing on educational achievement than physical factors such as weight at birth, a study reveals today.

The research, published in the British Medical Journal, provides fresh evidence that babies who are heavier at birth tend to grow up brighter and do better at school. But social class at birth has a greater effect on a child's cognitive development, with children of professional parents achieving better results than those from unskilled backgrounds.

The study is the first to examine the combined effects of birth weight and social background on academic achievement and on later adulthood.

The findings show that bigger babies from the top two social classes – the professional and managerial groups – tend to gain better results than those from social classes four and five, the unskilled groups. But children who are underweight at birth, and have the advantage of a well-off home, will outperform children who were heavier at birth but come from poorer backgrounds.

Researchers from the Institute of Child Health at London's Great Ormond Street Hospital analysed the educational achievements of nearly 11,000 adults born in March 1958. They compared the results of tests in maths at ages seven, 11 and 16 and the highest qualifications that were attained by the age of 33.

The results show that educational achievements improved substantially with increasing birth weight. For example, 26 per cent of men who weighed 2,500 grams (5.5lb) or less at birth achieved higher qualifications compared with 34 per cent of men who weighed 4000g or more (8.8lb). For women, the proportion increased from 17 to 28 per cent.

But social class had a bigger effect on the results in maths tests than birth weight, and it became more pronounced over time. When the highest qualification attained by the age of 33 was assessed, social class also had a greater influence than weight at birth.

The trend persisted after factors such as maternal age, breast or bottle feeding, parental education and number of children in the family were taken into account.

Barbara Jefferis, lead author of the study, said the results underlined the importance of policies to tackle social deprivation.