Sam Green’s first thought when she got arrested for fraud was whether she would be home in time to greet her children from school.

For 20 years, Green (not her real name) had worked in financial services. She was left in severe debt after being defrauded by her husband, and she stole money from her employers.

“I just saw the life I’d tried to build up collapsing and I couldn’t think of any way out of it,” said Green, 47, from Surrey, about what led her to commit the offence.

Although she was sacked and repaid the money to her employers by selling her house, she was imprisoned in December 2012 – more than a year after she was arrested. She left her two children, aged 12 and 15 at the time, in the care of her elderly stepfather.

“[Prison has] had a devastating effect. My family were ashamed and disappointed in me – that’s never going to go away,” she said. “I think prison should be the very last resort … [to be used] if someone’s dangerous.”

The number of women behind bars has not significantly fallen from the 4,000 that the coalition inherited from the last Labour government (Getty)

Green’s plight is one shared by the 12,000 women sentenced each year in the UK, a rate of incarceration that leaves about 20,000 children without mothers, according to Women in Prison. The situation has prompted the charity, along with the Centre for Crime and Justice Studies, to convene a conference in London next week called “Justice Matters for Women: Time for Action”.

The conference, which follows a call to action last year, will debate the criminal justice system’s perceived failures, alternatives to jail and measures to stop women offending in the first place.

Green served three months of her sentence in prison and the rest on licence, but said that a community sentence would have saved her from the stigma of a criminal record. “My life is over effectively … I can’t start again with a career. I’ll never own a house again. I’ll never be able to rebuild the relationships I’ve got with my kids.”

Women in Prison’s director, Rachel Halford, said imprisoning women has larger consequences than does locking up men.

Issues of domestic and sexual violence, mental health problems and substance abuse “led [women] into criminality”, she said. “Consequently, these are all issues that, had they been picked up and addressed earlier, these people may well have not ended up in the criminal justice system.”

More than 80 per cent of women who go to prison have committed a non-violent offence; in 2013, 40 per cent of those were imprisoned for theft or handling stolen goods. “A huge percentage of women commit non-violent crimes so they don’t need to be there – they’re not a risk to the public,” said Ms Halford.

12,000 women are sentenced each year in the UK (PA)

In 2007, Baroness Corston’s review of women in prison offered recommendations for a reform of the system, but Ms Halford believes not enough had been done since then: “The prison system as it exists today doesn’t work and that is evidenced by the high rate of reoffending and the rates of self-harm.”

Ms Halford advocates community sentences which she said cost around £30,000 less than prison. “So not only is it a saving to the public purse … it’s about the emotional damage that isn’t caused to the mother and the family.”

Rebecca Roberts, from the Centre for Crime and Justice Studies, said tackling structural inequality against women in society was key and that prison had become “a very convenient way for the Government to [deal with] particular groups of people and not really offer the support they need”.

“The harrowing thing is that often women in prison say: ‘This is the only place I feel safe.’

“The prison system is a tragedy. It is an inadequate response to social problems,” she said.

Ms Roberts said it was necessary to make sure that community services and women’s centres existed to support women with the issues that often led them to criminal justice, but she was concerned about funding cuts.

There are around 3,900 women in prison, having fallen from approximately 4,500 in 2004. Jenny Earle, of the Prison Reform Trust, wanted the number of women in prison to halve over the next five years, and investment in community services was vital to achieve this, she said.

“There are ways that are much more constructive for people to make amends for their offending … going to prison exacerbates the problems that women have.”