Three brave women have spoken about the realities of being non-custodial mothers.

Speaking candidly in Vimeo documentary The Last Taboo, Rebecca, from London, Sarah, from New York and American-born Maria admitted they have been judged, outcast and even told they should be sterilised, after they gave up custody of their children.

Highlighting the sexism that still exists in society, they questioned why men - who make up just 10 per cent single parents living with their children - aren't subjected to the same stigma.

Speaking in the eye-opening programe, the three women revealed the reasons behind their decisions, and how it has affected their lives.

Rebecca, 36, from London, mother of one son

Three brave women have spoken about the realities of being non-custodial mothers. When her son was 23 months old Rebecca's brother contacted her saying he was getting married, and she instantly knew this was her way out.

Rebecca told how she was squatting in South London with her Estonian partner at the age of 23 when she fell pregnant.

Realising they needed somewhere to 'nest', they decided to relocate to a remote part of Estonia before welcoming their little boy.

But within days the new mother felt she had made a huge mistake, telling how she felt like 'trapped bird in a cage'.

'When my son was weeks old I wanted to get out massively,' she says in the program.

'I felt like a caged bird. I didn't tell anyone what was going on or how unhappy I was. It was weird for a mother with her tiny baby to be so miserable and unhappy.'

When her son was 23-months-old, Rebecca's brother contacted her saying he was getting married, and she instantly knew this was her way out.

Rebecca left the town of Tallinn and now visits him a few times a year, and despite it being a hard decision, she now feels she can finally breathe.

'It's the most normal thing in the world for fathers to [not have full custody] and yet I've never met a single woman who has done this,' she says.

Natalie, 34, New York, mother of a boy and girl aged four and six

Natalie made the tough choice to leave the family home after four years, her ex husband gaining full legal and residential custody

Natalie was pressured into getting married at 26, by her religious family who she says told her that her 'lack of looks, money or job' meant she must take up the offer.

Remembering how she felt it was a mistake as soon as she walked down the aisle, she continued to try to feign marital bliss, welcoming two children - a girl, now six, and a boy, now four.

But despite appearances she felt wildly unhappy and unfulfilled.

'I felt my brain was melting. Here I was stuck with a baby at home while other women were travelling and working and exploring the world. I never told anyone I was struggling. I put on a happy face,' she says.

After four years she made the tough choice to leave the family home, her ex husband gaining full legal and residential custody.

Natalie, who is now an office manager and sees the children regularly says she was ashamed at first, but didn't feel perfect enough to be a mother.

Speaking about people's reactions, she says: 'They say, 'What do you mean you don't have custody of the kids? It's one of the last taboos.'

Maria, from America, mother-of-four

Maria was just 20 when she got married, before having her first of four children aged 25. Admitting that she felt 'incredible pain' as she drove away from the house, Maria also admitted she felt a sense of relief and possibility

Maria was just 20 when she got married, before having her first of four children aged 25.

Right from the start Maria battled to feel like a 'normal' mother, turning to magazines to figure out what she should be doing.

And despite continuing to do her best as a wife and mother, she says she always felt 'another life feeding underneath the surface of my skin'.

Tragically Maria lost her second daughter to cancer just a month before she was due to turn four.

The overwhelming grief she felt proved to be the catalyst which led her to moving out.

Admitting that she felt 'incredible pain' as she drove away from the house, Maria also admitted she felt a sense of relief and possibility.

Maria felt the decision was right for her children, as well as letting her discover who she was as a person - not just as a mother and wife.

Having spent the majority of her younger years as a wife and mother, she admitted that she only started having rebellious moments such as smoking in her early forties.

Explaining that society should rethink their ideal, she says: 'Sometimes it is better for the children and the family if the mother moves out.

'I definitely felt judged as a mother. I was told that I should have been sterilised and not allowed to have children'.