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Very low birthweight predicts lower exam grades at the age of 16

March 21, 2003

Severely underweight babies grow into adolescents who achieve lower exam grades, finds research in the Archives of Disease in Childhood.

The research team retrospectively investigated the exam results of 334 16 year olds sitting their General Certificate of Secondary Education (GCSE) in Merseyside, North West England. A numerical score was given to each GCSE grade, starting with 8 for A*, to 1 for a G grade. Half the children had weighed 1500 grams or less at birth; normal birthweight is between 2500 and 3500 grams.

Between 1980 and 1981, 399 babies weighing less than 1500 g were born, of which 215 survived to the age of 15. After excluding those who had a disability, and failing to trace some children, 167 were paired with normal birthweight children who had attended either the same primary or secondary schools, or both.

The researchers also looked at the results of formal intelligence (IQ) tests, which the children had taken at the age of 8. And they assessed various influential factors, such as social class, employment and housing status, parental education and income, and number of children in the family.

More than 140 of the 167 pairs sat at least one GCSE exam subject. The results showed that the normal birthweight group scored significantly more points, overall (36.78 compared with 32.33), and for each subject examined (4.26 compared with 3.83).

In terms of exam grades, the normal birthweight group scored almost half a grade higher for each subject, achieving an average subject result between grade C and D, while this was between D and E for the low birthweight group.

The normal birthweight group achieved significantly better grades for mathematics and statistics and higher grades in general science, English and English Literature. Both groups achieved similar results for geography and history.

The authors point out that academically able children may take science subjects separately. Among the normal birthweight group, 19 took biology, 18 took chemistry, and 17 took physics. Among the low birthweight group, the corresponding figures were 9, 8, and 8, respectively.

The national average for children achieving five or more subjects at grade C or above in 1997 was 45%. The normal birthweight group achieved 44%; the low birthweight group achieved just over 38%.

Children who scored more highly on the IQ test at the age of 8, achieved significantly better GCSE results.

The authors conclude that very low birthweight clearly affects subsequent intellectual and academic performance, which may influence employers' selection criteria, as well as the chances of entering further education.

They suggest that the factors affecting the spurts of rapid brain development during pregnancy and soon after birth are substantially more important than the social environment or the quality of school education.

British Medical Journal (BMJ)