Half of women headteachers in secondaries have had to fight sexism to win promotion, a government-backed study has found.
Many women struggle to balance increasing school responsibilities with bringing up children and their attempts to climb the career ladder are often blocked by male-dominated interview panels and sexist governors.
Researchers say reasons given to women who failed to win headships included wearing too much nail varnish or gold jewellery, being too short, and not supporting boys' sport.
One woman in her mid-40s said she was asked to withdraw her application for a senior teaching job after revealing she was pregnant. According to the report, governors greeted one woman primary head in an interview with: "Oh good, it's the one with the legs."
And a secondary head in her early 40s told the researchers: "I was asked at interview what my husband would say if I were appointed."
The findings were revealed this week as the first programme to attract more women heads and deputies was launched by the National College for School Leadership.
Latest government figures show 31 per cent of secondary heads are women, even though 55 per cent of secondary teachers are female. In primary schools, women make up 84 per cent of the teaching force but hold only 62 per cent of headships.
The study, commissioned by the college, said 50 per cent of female secondary school heads experienced "sexist and discriminatory attitudes" at some point in their careers. A third of women in charge of primary schools encountered similar barriers to promotion.
The number of women heads has increased by around 5 per cent since 1997, but Dr Marianne Coleman, of London university's institute of education, who carried out the study, said: "There is still a common expectation that a headteacher, particularly of a secondary school, will be a man."
Survey responses from 725 women heads showed that pressures in the home, combined with an increasing workload, were the biggest barriers to promotion.
One woman head felt she was forced to take only four weeks' maternity leave to prove to governors that she could combine parenthood with headship.
Another said: "I was interviewed for headship one week after having my second child. I was breast-feeding in the car outside, as no provision could be made in the school."
Geraldine Freear, head of a federation of two Roman Catholic secondary schools in Brent, north-west London, said her husband had to give up his job and look after their two daughters to enable her to work.
"A woman secondary head with a young child is a relative rarity," the study concluded. Male-dominated interview panels were also blamed for failing to encourage women into senior jobs. On average, there are six men to every four women on these panels.
Jane Lees, head of Hindley community arts college, Wigan, who has a grown-up daughter, was told by one governor when she was interviewed for a previous job: "You should be at home looking after your children."
The new NCSL programme, "Taking Women's Leadership Forward", includes sessions on assertiveness, managing relationships with colleagues and career planning.
Recruitment analyst John Howson, a visiting professor at Oxford Brookes university, said that the report's conclusions were "over-simplistic".
"There is no evidence that putting on a special course is the appropriate answer to getting more women into senior management roles," he said.
For more details see www.ncsl.org.uktwlf