Research by a law firm has suggested that many women feel discriminated against by employers when they start a family. More than half of those surveyed thought the attitudes of colleagues and bosses changed after they got pregnant, while a quarter said they had lost out on promotions, had work taken off them or been demoted.

A third of the 1,975 women questioned by legal firm Slater and Gordon said they found it impossible to climb the career ladder, yet 35% thought they worked harder since having children.

Sadly, in my experience, these findings are typical. When I was pregnant, I joined an antenatal group of eight women in south London who worked across a broad spectrum of careers. Two years on, only half of us work – stress and discrimination has driven the others from their jobs.

For some of the mothers in my group, the problems started before their babies even arrived. One who worked as a chief executive for a charity didn't quite get the response she expected when she announced her pregnancy to the trustees. "My news was met with anger," she says. "I was told: 'no one ever comes back after having a baby'. The previous chief executive had been a man, so the charity had never experienced anyone going on maternity leave. I just carried on working, but people withdrew their support and I was very under-resourced."

Her colleagues began to sideline her in the office, so she opted to work from home when possible, but began receiving bullying emails and phone calls. She worried that the stress was affecting the health of her baby, went on maternity leave early, and decided to resign before the birth. Once her child was born, she filed a tribunal claim to be able to get a reference from her employers, who also wrote a letter confirming that she had done nothing wrong.

Another mother was sacked from the PR firm she worked for, just a few days shy of having been there a year and the day after she discovered she was pregnant. She hadn't broken the news to her employers, but her boss knew she was trying to get pregnant, and she feels that was behind the decision.

"When they fired me they said that I was not considered a team player, and had to leave the office immediately with all my belongings," she says. "There was no disciplinary procedure whatsoever, so I started with tribunal proceedings. The legal adjudicator said he could see a strong case for sex discrimination, but felt the tribunal process would be too stressful for my pregnancy, so we settled out of court and I was made to sign a non-disclosure agreement."

One of the group went back to work, as an architect at a firm she had been at for 12 years. She was made redundant several months later, along with most of the female architects in the practice. Before that, even though her employers had been accommodating in terms of honouring her flexible working hours, she found herself demoted from her usual responsibilities. "When I queried this people would say 'it's difficult when you're doing four days a week', or 'you need to leave at 4.30 so don't worry', which I found patronising," she says. "In the end they got rid of 70% of all female architects and assistant architects, who, bar one, were mothers. We were all very good at our jobs and there had never been any problems before."

Even those who were not forced out of work have struggled. I went back to work part-time as a project manager at a television company a year after my daughter Erin was born. I was nervous but excited about returning, but in the end the volume of work became too much. When this was mixed with having to leave at set times to collect my daughter from nursery, I ended up doing a lot of overtime in the evenings and on the days when I was meant to be looking after her. I gritted my teeth and tried to get through it, but then the stress started to affect my health. I tried to think of all kinds of solutions to make the job work, but reached a brick wall.

Workplace obstacles for both pregnant women and those returning to work after maternity leave appear to be growing across all industries, and many barriers stand in the way of women who want to work, but also have a family. The charity Maternity Action, which provides information and advice to pregnant women, new mothers and their families, currently receives 15 times more calls than it can answer to its advice helpline, and reports that downloads of its online factsheets have doubled each year for the past three years. Ros Bragg, director of Maternity Action, says: "We get a lot of calls where women have returned to their old job and find that it has changed in a way that makes it impossible to continue in that role or organise childcare. Women are swiftly selected for redundancy. This is very difficult to combat."

She adds: "Women are at their most vulnerable when pregnant or with a new baby and it's very disappointing that employers take advantage and treat women badly. The government should be intervening instead of leaving it to the individual."

If you find yourself worried about discrimination at work, Ros Bragg states that there are ways to protect yourself: "Women should know what their rights are, because employers don't expect them to be informed. Keep detailed records of conversations and emails, and be prepared to submit a grievance if needed. Check your home insurance policy because many offer legal cover."

All four of us have since found it difficult to find new work that fits around our childcare needs, but we take inspiration from another mother in our group, Thea Hickson. She has experienced a positive return to work at television production company Wall to Wall. "I decided I only wanted to work two days a week and my company created a job for me that would fit, and I now do a jobshare with another mum. We work the same days together, and it's great to have two heads rather than one on projects. And if I can't make shoots or meetings, the company never makes me feel guilty. Everyone really likes working there – they feel happy, valued and privileged and give 150%. The company accepts you as your life changes."

Was your experience of returning to work good or bad?

Anne Richardson writes the blog Toastandbutter.net