Francesca Warren, a 45-year-old saleswoman, was a respected senior member of the team, but when she announced her pregnancy everything changed. She says: "They immediately employed someone else, then took two of my biggest clients off me and gave them to her."
Francesca took legal advice, but at the time decided not to act. She says: "I was 40 at the time; I was lucky to be pregnant and I felt that avoiding stress for the baby was more important than how I was being treated."
She went on maternity leave in December 2003. The following month, the company said she wasn't entitled to the £30,000 to £35,000 commission she was expecting. Then, shortly before she was due back to work in December 2004, she was fired. She launched a case in early 2005.
The process was harrowing. It took almost a year to have a hearing scheduled. She says: "It was stressful. It put my marriage under huge stress and we have since separated. It also made it extremely difficult to find another job. I had been fired, which wasn't great for job interviews, and I work in an industry where everyone knows each other's business, so everyone knew about the case."
In the end, her former employer settled on the day of the tribunal. She says: "I felt I had given them a bloody nose. They had treated people badly in the past because they thought they could get away with it, and I proved that they couldn't."
Francesca has since established her own business. She is comforted by the fact her former employer will think twice about future discrimination, but there are plenty more employers out there with similar views.
A survey by the Equal Opportunities Commission a few years ago found 45% of women who had worked while pregnant in the previous three years experienced discrimination. Some 21% lost out financially, and 5% were put under pressure to hand in their notice as soon as they announced their pregnancy.
Nowadays, discrimination tends to be subtle rather than overt. So, for example, when a woman announces she's pregnant, a company may fire her, or start performance management procedures, for an issue that's supposedly completely separate from her pregnancy.
Samantha Pierce, a 27-year-old mother, started working for an estate agency soon after discovering she was pregnant. She says: "I settled in well, and was told by the branch manager that I was doing a great job. I hadn't told them I was pregnant when I took the job, but announced it after my scan at 15 weeks.
"The following morning, I had a letter from the office manager who listed a load of things I hadn't been doing to her liking. I was called to a meeting and received an official verbal warning. Then my boss lost it, and what he said showed this was entirely about my pregnancy."
Eventually, after more confrontation, Samantha quit, and has decided to stay out of the workplace while her children are young.
Alternatively, pregnant women may find themselves sidelined. This happened to Rebecca Jones, a 32-year-old administrator, while she was on maternity leave. "A colleague, who was one grade below me, covered my role while I was away," she says. "During that time, my role evolved and they created a new job, which took away a fair chunk of what I had been responsible for.
"The colleague who was covering me was appointed to a new post, which was a grade higher than mine. The first I heard of this was when he emailed me to let me know. As well as being annoyed that I wasn't given the chance to apply, it also meant that my role had changed considerably."
UK representative of women's rights in Europe, Mary Honeyball MEP, says employers must work harder to ensure women aren't forgotten while they are on leave. "There are ways of updating women about what's going on. It's unacceptable for them to be 'out of sight out of mind'," she says. "That's one of the reasons the law permits women to be 'kept in touch', so they can be informed about everything that's happening."
Alternatively, an employer may make returning to work difficult. This may be through issues surrounding flexible working. Hope Jones, a 29-year-old project co-ordinator, says: "I made it clear I wanted to work part-time from when I was first pregnant. My boss agreed, but didn't do anything to make it work, so me being part-time affected the workloads of the rest of the team and created a lot of bad feeling. It made my return to work very difficult."
Women are vulnerable at these times, but they have certain rights. In the first instance employers must ensure they are not exposed to risks at work, they must also give paid time off for antenatal care, and treat employees fairly.
Jane Moorman, head of employment at law firm Howard Kennedy, says: "A tribunal will take into account whether someone has been treated in the same way they would have been if they hadn't been pregnant."
In addition, you cannot be fired or selected for redundancy for any reason connected with pregnancy or maternity leave. Esther Smith, a partner in the employment law department at Thomas Eggar, adds: "There's a peculiar rule that if you are made redundant while on maternity leave, if there is a suitable alternative job within the organisation, you have an automatic right to be offered it."
Women also have the right to request flexible working hours on their return, although the employer only has to show the request has been fairly considered.
There are a host of online resources including sites such as babycentre.co.uk, or babyworld.co.uk, which can also connect women with others in the same situation.
However, a lot of women, even if they know about their rights, do not assert them. Many women don't want the stress of confrontation, may want to avoid the stigma associated with suing their employer, are worried about losing their job if they complain or are put off by the process, which is far from ideal.
Joanna Downes, an associate at Clarion Solicitors, explains: "In most cases, a claim needs to be brought within three months of the incident, or if there were a string of incidents it must be within three months of the last one."
Then there's the long wait for the tribunal. Downes also points out: "The timing can be difficult, if the incident happens towards the end of a pregnancy and the individual has to launch a case at a difficult time, or if it happens at the beginning and it gets to tribunal in the later stages of pregnancy."
It may also be difficult to prove a case. "The employee has to show there's no explanation for the treatment besides the pregnancy," Downes adds.
Making this case isn't easy. Lauren Harkin, an employment solicitor with Lemon & Co solicitors, says: "If there have been previous issues relating to performance and warnings have already been given, or if following the announcement of the pregnancy there's a three-to-six-month period of performance management, it will be more difficult for the dismissed employee to say it was an act of discrimination."
You can help your case by keeping a diary of discrimination, or any relevant emails.
Likewise, it's hard to prove discrimination when a right to request flexible working is refused. Moorman says: "There are lots of defences an employer can bring. If they have legitimate reasons not to grant it, the law will support them."
However, Stephen Ross, a solicitor with law firm Withers, says: "It's always possible to make a case, even when it's a ''he says, she says' case. We can send the employer detailed questions on the incident. If they answer, they may realise you have a good case; if they don't answer, it looks bad for them in any tribunal.
"However, the more evidence you have, the easier it is."
Francesca Warren was lucky enough to have legal cover on her household insurance, which covered all her bills. Alternatively, some firms offer a no-win no-fee service. Moorman adds that trades unions may be able to help.
If you can afford the process, and have the strength to see it through, there are compensations for women who take their employer on. While emotionally draining, Honeyball says: "The more employers who can be persuaded to re-think negative attitudes towards pregnancy, the better. Employers need to understand that women get pregnant, and it's essential that they do. They can't be punished for it."
* Names have been changed