Girls are continuing to outperform boys at A-level, figures show.
Exam reform should be gradual and considered, a teachers' leader will say
In fact, at the top end the gender gap is widening, with the growth in the number of girls gaining grades A to C being greater than the rate among boys.
This year, 70.7% of grades awarded to girls were in this category, up 2.3% from the previous year.
For boys, there was a rise of 2.2% to 63.8%, the Joint Council for General Qualifications, which represents exam boards, found.
Martin Ward, deputy general secretary of the Secondary Heads Association, said this was a reflection of girls' greater teenage maturity.
He added: "They are more likely to work steadily throughout the course.
"With the emphasis moving more towards continuous assessment at A-level, rather than last-minute exams, this is bound to help them. It could be they are simply better than boys at this."
Mr Ward, who was principal of Wyke Sixth-Form College in Hull until last year, said: "The rise in girls' achievements is an example of them reaching their true level.
"Before, they were held back by the system. Now that is not so much the case."
The A-level pass rate (grade A to E) for girls was 96.4, while for boys it was 94.3. For the genders combined, the figure was 95.4%.
The only major subject in which boys had a higher pass rate was German - 97.7%, compared with 97.3%.
The sexes were evenly matched in chemistry and business studies.
Overall, girls took more A-levels than boys - 404,855 compared with 345,682.
Mr Ward said: "When I was teaching, you noticed that the sixth form was becoming a more female environment.
"At GCSE level you have the question of so-called 'lad culture', which, it has been said, often takes boys away from higher achievement.
"This can lead to male students starting sixth form later than females, when they realise they are in dead-end jobs or want to go further in life."