Image copyright Joeli Image caption Joeli Brearley was shocked at the numbers of women coming forward

In a few months' time the Equality and Human Rights Commission will publish results of a £1m study that campaigners say will show a huge rise in the numbers of women suffering discrimination because they are pregnant or taking maternity leave.

A new project called Pregnant Then Screwed says it's already exposing the scale of the problem and is hoping to build a case for change.

"My colleagues all got promotions when I was on maternity leave..."

"I was placed in the most junior role to ease me back in..."

"She didn't think women with under-fives should work..."

A quick scan of the Pregnant Then Screwed website gives a snapshot of the way many women are being treated when they announce their pregnancy to their employers.

The site's founder, Joeli Brearley, 36, experienced discrimination when she was pregnant and was shocked by how many similar stories she heard when she spoke to other mothers.

"The problem is women are too scared to speak out for fear of being branded a troublemaker. Or if they still work for the company they are terrified of losing their jobs, particularly now that they are responsible for a child," she told the Victoria Derbyshire programme.

"You also only have three months to take a case of discrimination to an employment tribunal, and this tends to come at a time when you are weak, exhausted and frankly, this just isn't your priority.

"It all just gets brushed under the carpet."

Case study: Charlotte, 31, from Scotland

"I left my job recently after nine years.

My employer was supportive of me working flexible hours after my first baby, but I got pregnant with my second baby almost straight away.

They took me off any interesting contracts and made me do admin, all under the cloak of 'you won't want to stay late because you have a family'. But I would have liked to have done something more interesting; I just put up with it because I knew I would be leaving again.

When I returned after my second maternity leave they said I could stagger my return, starting with three days a week, which would be reviewed after six months.

But six weeks before this was up, my line manager told me I had to come back to work full time or leave. No negotiations, and flexible working was not on the table. I told them childcare would cost more than my pay.

I was really angry - I didn't want to be part of a company that showed such little loyalty for all my hard work.

I am suing for constructive dismissal as the person they have replaced me with is working part time. Acas, a conciliation service, says I have a strong case for breach of contract. I deserve some compensation for the stress it has caused."

The first legislation protecting women from unfair dismissal because of pregnancy was introduced 40 years ago. Since then, successive laws have strengthened maternity rights. Women are now protected from any unfavourable treatment at work because of pregnancy or maternity leave.

But nine years ago, research from the Equal Opportunities Commission (EQC) found half of all pregnant women suffered a related disadvantage at work, with 30,000 forced out of their jobs each year.

Others are demoted, suffer harassment, miss out on promotion or lose contracts if they are self-employed.

The charity Maternity Action now estimates as many as 60,000 pregnant women are losing their jobs every year - an increase which they put down to the "explosive growth in precarious forms of employment" since the financial crisis.

They applied the same methodology as the EQC - taking the number of people who went to tribunal and taking into account that this was only 3% of actual cases.

Ms Brearley was self employed as a project manager in art and digital technology, and had been working with her main client for six months when she told them she was pregnant. They ended the contract, despite her meticulous planning to cover her absence.

"I suddenly found myself four months pregnant and pretty much unemployed. It was terrifying," she said.

"There was no way I could survive the next five months plus maternity leave without a good income as I had bills to pay, but no-one was going to employ a visibly pregnant woman.

"I became very stressed, felt very alone and vulnerable, and it totally shattered my confidence," she said.

Image copyright Danielle Image caption Solicitor Danielle Ayres has been treated well by her employer, but while she was on maternity leave she encountered many women who were having problems

When Danielle Ayres, 32, an employment lawyer for north west firm Gorvins Solicitors, attended baby groups with her first son, she was astonished at how many mothers she heard saying they were having issues with their employers.

She soon found herself dishing out legal advice amid the chat about teething and sleep training, and now runs free advice clinics every six weeks. The take-up has been "huge", she said.

Her cases include one woman who, after informing her boss she was pregnant, received the reply: "I hope you aren't going to be taking the full 12 months off."

Another returned to work to find that a reorganisation had taken place while she had been on maternity leave and that she had no desk or job.

"Mums don't really know their rights, what they're entitled to and how they should be treated," said Mrs Ayres.

"Some employers hit the nail on the head and manage pregnancies and maternity leave to the letter, and they really know how to support working mums.

"But others - either by fault or design - get it completely wrong, and it's really deeply disappointing that in the 21st Century people are facing these challenges."

Main maternity rights

Maternity leave of up to a year and pay for 39 weeks

Reasonable paid time off for ante-natal appointments (and the ability for partners to accompany you)

Contractual rights should continue during leave, including accrual of holidays and pension contributions

The right to return to the same job if up to 26 weeks' leave is taken, and the right to return to a similar position if over 26 weeks

Protection from redundancy, dismissal, and detriment due to pregnancy/maternity leave

Source: Maternity Action

Mrs Ayres said the main problem lawyers face is connecting the treatment the woman is receiving from employers to her pregnancy, or the fact that she has exercised her right to take maternity leave.

"You need to be able to show that the treatment, which can include dismissal, is as a result of the pregnancy or maternity, which is sometimes difficult to prove," she explained.

Moreover, in 2013 a £1,200 fee was introduced for anyone wanting to take a case to a tribunal. Since then the number of cases being taken for any reason - not just maternity discrimination - has dropped dramatically by 70%.

The first thing Ms Brearley is campaigning for is to increase the time limit for taking cases to tribunal from three months to a year.

In the six weeks since the project launched, about 50 stories have been posted on the site. She says many more women have contacted her to say they are too scared to share their stories, despite it being anonymous.

"But reading the stories of other victims has made them realise they are not alone and that this isn't their fault. It has given them the strength to confront their own situations," she said.

"I hope we can trigger a public debate on why this is still happening, why it's on the increase, and the repercussions for women, the economy and society as a whole."

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