A bestselling St Albans author was held captive in the world of criminality when writing her latest book.

Angela Clarke was inspired to write On My Life while she taught creative writing in prisons around the UK.

As there are currently only six Mother and Baby Units (MBUs) around the country, Angela met incarcerated women who had been separated from their children or were unsure about their unborn baby's future.

The fiction book follows a women called Jenna, who comes home one day to find her step daughter killed and her fiancé missing.

Framed for the murder, Jenna must prove her innocence and investigate who framed her - and all while pregnant behind bars.

Angela said: "I work in a number of prisons across the UK and I was shocked to learn that there are women inside who are pregnant.

"I wanted to write about it and shine a spotlight on the issue, as well as telling a good story as well."

She raised questions about whether women who are the primary care giver for children should be given custodial sentences for non-violent crimes.

Angela said she once attended a class where inmates were learning how to create homemade Christmas presents for their children on the outside with limited materials.

It left her in tears: "I came home and cried because it was really sad, and at Christmas time. They were trying their best to be positive and upbeat in the difficult situation."

Another inmate told Angela she had taken the fall for her teenage son when police had found drugs in their house.

"I think for serious crimes they need to be punished [with a custodial sentence], so that needs to be maintained in a practical way, but if it is small, petty, nonviolent crimes, then maybe not because if they have a child there are long term ramifications for the child as well," she said.

"I found writing the book really emotional, I put a lot of real life into it to make it as realistic as possible."

The 400-page book was published by Hodder and Stoughton on July 11.

Angela was named a Sunday Times bestselling author for the Social Media Murders series, and her 2015 debut novel Follow Me was named Amazon's Rising Star Debut of the Month.