The achievement gap between male and female students at age 19 has closed over the past three years, figures released by the Department for Education reveal.
Almost 58 per cent of students achieved level 3 - equivalent to two A levels - in 2012, compared with 56.7 per cent in 2011, statistics show.
Girls have consistently outperformed boys, with the performance gap growing between 2005 and 2009.
However, when A levels were changed in 2010 to consist of four modules, rather than six, and to include more open-ended questions, the gap began to shrink.
The government plans to reform GCSEs and A levels to make them more linear by scrapping modules and having students take exams at the end of their courses.
Geoff Venn, a retired chemistry teacher and former chief examiner from Bedfordshire, told the Association of Teachers and Lecturers' annual conference last week that the changes could discriminate against girls.
The gender gap at age 16 based on the number of students achieving five good grades was very slight between 1975 and 1987. But after the introduction of GCSEs in 1988, which put more weight on coursework, girls have pulled away.