The study, of around 375 AS-level students from across Wales, reveals that 41 per cent of the female students would have dropped the subject at the end of Year 9 - compared to only 15 per cent of boys.

Rosemary Jones, from the school of education and lifelong learning at University of Wales Aberystwyth, was looking at why fewer girls than boys carry on with maths at AS-level. But her research suggests that the gender imbalance would be even more pronounced were the subject not compulsory until 16.

In 2002-3, only 39 per cent of AS maths students were female, despite roughly equal proportions of boys and girls achieving A*-C grades at GCSE.

Questionnaires completed by Y12 pupils showed more than half of female students felt anxious during maths lessons, compared to only around a quarter of males. And more boys enjoyed maths (57 per cent) than girls (43 per cent).

Only a fifth of girls predicted they would get an A grade compared to more than a third of boys. And while similar numbers of boys and girls intended taking the subject to A-level, just over a third of girls were considering a maths-related subject at university, compared to two-thirds of boys.

Ms Jones found that in schools and local education authorities which had addressed inequalities, more girls were likely to be taking AS-level maths.

Initiatives included single-sex teaching, mixed seating, role modelling and staff training. But while 77 per cent of LEAs surveyed said gender differences were a concern, more than half of teachers were not worried.

Why do more males than females continue with maths post-16? by Rosemary Jones jones@oakfield16.fsnet.co.uk