Dr Rachel Dolan has been researching the experiences of women in prison since 2007 and says the level of support for women behind bars is a lottery, based on inadequate support from children’s services.

Dr Dolan says: ‘Pregnant women are a very small proportion of the overall female prison population, which in total is around 4,000 women.

‘Nonetheless the impacts of being in prison while pregnant are huge for the women and their unborn children.’

Each year, approximately 120 women give birth whilst in English prisons.

Dr Dolan added: ‘Levels of stress and anxiety have a detrimental impact on a child, some women don’t even know right up until the point of labour whether they can keep their child once he/she is born.

‘Sometimes the hands of prison staff are tied and social services make those decisions, but the delays are frustrating for women’.

Under current rules, women who give birth in prison can keep their baby for the first 18 months in a mother and baby unit (MBU).

In an MBU conditions are slightly more relaxed, with prisoners and babies sleeping in unlocked rooms rather than cells, with a small children’s play area set up too.

A prisoner with a child under 18 months old can apply to bring their child to prison with them to the unit.

If the child is over 18 months, social services then make arrangements for the child to be cared for by the prisoner’s parents, or place the child with a foster family.

However, Dr Dolan says the requirements of who can apply for an MBU puts many women at a disadvantage.

There are only six prisons with an MBU unit in England, with 65 places for mothers and 69 for babies.

Dr Dolan claims that the ability of a pregnant prisoner or a prisoner with children under 18 months old to make a successful application to be placed in an MBU unit is dependent on what prison women find themselves in as well as their criminal conviction and length of sentence.

She said: ‘There aren’t that many women prisons, many are placed in prisons far away from home, these factors play a part.’

Dr Dolan added that the application process to be put in an MBU was very slow, with subjective criteria such as the women’s ‘behaviour’ also taken into account.

She added: ‘The prisons and mother baby unit is a very slow process, when social services become involved it’s even slower’.

Dr Dolan added that on some occasions, when the decision is made, it is too little too late, with the child already in foster care, making it harder for mothers to be reunited with their children.

She added that the bar for separating children from their mothers was ‘lower in prison’, given that the overarching priority was always prison security.

The closure of MBU units meant that in some cases, women were being left to give birth in maternity units hundreds of miles away, the reported.

Comparing Britain’s system to countries like Germany and the Netherlands, Dr Dolan said that elsewhere pregnant women and those with young children were able to have their sentences deferred, to allow them the time to make preparations for the care of their children.

She also says that the 18 month limit on children was also a lot more flexible, highlighting the example of Germany where the limit is set at 6 years old, with mothers and their children placed in more open mother and child houses.

Dr Dolan added: ‘I think the main issue is, we (England and Wales) have the highest rate of incarceration in Western Europe, in other countries they just don’t have as many women being sent to prison in these countries.

‘They provide alternative provision within the community.

‘It’s not just about being critical of the prison service, it’s the entire system that’s politically motivated’.

A Ministry of Justice spokesperson said: ‘Our units provide a safe environment for mums and babies at an important time for bonding and development and there are no plans to close any.