"A woman's IQ halves when she falls pregnant", her boss allegedly said.

“A woman’s IQ halves when she falls pregnant”.

It’s the sort of shocking claim you might expect to hear from an ignorant adolescent — not from an educated director at a prominent stockbroking firm.

But that’s exactly what one former JBWere executive director alleges her supervisor said when she told him she was pregnant.

Now, the Queensland banker is alleging she was sexually harassed into leaving her position after falling pregnant — and she’s claiming nearly $4.5 million in compensation.

According to Fairfax Media, Antonia “Toni” Thornton alleges the harassment began when she revealed her pregnancy to her supervisor in January 2009, 

Federal court documents filed in August claim Ms Thornton’s then-supervisor, Paul Heath, responded to her news by saying that in his experience, “a woman’s IQ halves when she falls pregnant”.

Three months later, Mr Heath — who is no longer with the stockbroking firm — allegedly told her to turn around for him, then commented on her pregnant body: “Yup, you are having a boy because your bum has blown out”.

Court documents also allege that when informing another colleague she planned to take maternity leave to have her second child, he said he was “pissed off” and “frustrated”.

Mother-of-two Ms Thornton also claims human resources staff stold her to ignore, rather than report, the incident.

It is also alleged she was also repeatedly asked: “Do you really want to come back to work?”

Ms Thornton’s claims are jaw-dropping — but frighteningly, recent findings by the Human Rights Commission indicated that such attitudes to pregnancy and maternity leave are all too common.

Sex discrimination commissioner Elizabeth Broderick said while she couldn’t comment about this specific case, a survey by the commission had found that workplace discrimination during pregnancy, during parental leave or on return to work was “systemic and pervasive”.

“What that study found is that 49 percent of mothers experienced discrimination at one point,” Ms Broderick told Mamamia.

“It was things like demeaning attitudes… right through to women being told ‘your choice, the job or the baby’, some of whom were ultimately dismissed.”

Ms Broderick said the study — the most in-depth work on this issue ever conducted in Australia –found that 18 per cent of working mothers were “made redundant, restructured out of the role or in some other way exited out of the workforce” before or after having a baby.

The report also revealed that 32 per cent of all mothers who were discriminated against went to look for another job or resigned.

“It is quite shocking,” Ms Broderick said. “What we do know is that pregnancy and return to work discrimination is a major barrier to women’s full and equal participation to paid work.”

She added the problem was “not at all” restricted to one industry, or level of seniority.

“What we’ve found is it’s systemic and pervasive,” she said. “It crosses all forms of the labour market — from the most disempowered workers, to senior executives in the medical, the legal, the corporate worlds.”

“There’s no particular industry that’s better or worse,” she said. “It’s quite ubiquitous.”

Employment law specialist Daniel Victory, from plaintiff law firm Maurice Blackburn, told SmartCompany it is likely Thornton is seeking damages for loss of earnings, hurt and humiliation.

“Employers are liable for the conduct of their employees,” Victory told SmartCompany. “But under discrimination legislation, they may not be liable if they can show they have taken all reasonable steps to prevent harassment and discrimination from taking place.”

The case will return to the courts in November.

Have you experienced harassment or discrimination at work because of pregnancy or being a new mum?