Women in prison are five times more likely to have a stillbirth and twice as likely to give birth to a premature baby that needs special care, new data collected by the Observer shows.

Following two baby deaths in prisons since 2019 there have been increasing concerns about safety for pregnant women and their babies.

Figures obtained through freedom of information requests made to 11 NHS trusts serving women’s prisons in England show 28% of the babies born to women serving a custodial sentence between 2015 and 2019 were admitted to a neonatal unit afterwards – double the national figure, according to data from the National Neonatal Research Database.

Of the 125 births for which additional data was supplied, one in seven babies had a low birth weight – double the rate in the general population. Stillbirths were at a rate of 20.9 per 1,000 births, compared with 4.2.

The findings come as the House of Lords prepares to vote this week on proposed changes to bail and sentencing laws that would improve the rights of pregnant women and mothers facing criminal charges.

One woman, known only as Anita, who was six months pregnant when she was arrested, gave birth while on remand and said her son would never have spent the first weeks of his life behind bars had she initially been granted bail: “Every pregnant woman is offered a single cell but I refused as my biggest worry was giving birth on my own behind a locked door,” she said.

A report published in September examined the circumstances of a baby’s death at Bronzefield prison in Surrey where an 18-year-old was left to give birth alone in her cell. Research shows one in 10 women who give birth during a prison stay do so there or on their way to hospital.

When Anita rang her cell bell at 5.30am when she went into labour the guards said they would send somebody. It was only during the morning rounds at 7.30am that a nurse was called. She was transferred to hospital at 10.30am. Anita said: “Despite being in active labour the guards would not remove my handcuffs and ignored me when I asked them to call the baby’s father and my mum – who were eventually contacted by a doctor.”

After her son was born, Anita wanted to breastfeed but instead asked for a bottle because the male prison guard would not leave her side and she felt uncomfortable. “It’s just degrading. It’s meant to be the happiest moment of your life but there you are being taken back – cuffed and with my son in a car seat,” she said.

Her solicitor later made a successful bail application and Anita was released on an electronic tag before being sentenced. She spent time on a mother and baby unit and was released just before her son’s first birthday. He suffered from bronchiolitis and during their time in prison he was taken to hospital 11 times.

Anita said: “Prison is simply not a safe place for pregnant women or children.”

Kate Paradine, chief executive of Women in Prison, said: “When a parent goes to prison it disrupts children’s lives and damages mental health, with nine in 10 children forced to leave their home when their mother is imprisoned.

“Homelessness, instability and trauma are just some of the consequences. Sentencing guidelines already acknowledge these devastating effects but there is clear evidence these aren’t being accurately or consistently applied.”

If amendments to the police, crime, sentencing and courts bill are passed, judges will be required to state how the best interests of a child or unborn baby are considered when sentencing a pregnant woman or primary carer.

“Currently the court looks at the woman in the dock and her children are invisible,” says Harriet Harman, Labour MP and chair of the joint committee on human rights, which drafted the amendments.

Harman, who oversaw a 2019 report on the the right to family life, said: “We have signed up to the rights of the child being paramount and yet we trample all over those rights when it comes to the children of women in prison.”

Responding to the data on stillbirths she said: “The findings are shocking and shaming but not surprising.”

A higher rate of drug and alcohol problems within prisons than in the general public could be one of many contributing factors to the poorer birth outcomes. The government’s own impact assessment for the bill’s measures indicate that 74% of women serving short sentences of up to 12 months had a drug misuse need.

Prisons are extremely stressful and traumatising environments that can affect a mother’s pregnancy, said Paradine. She explained: “For pregnant women who arrive in prison with pre-existing mental health needs, these are amplified and can be a cause of toxic stress that can affect the baby’s development.”

Janey Starling, co-director of the campaign group Level Up, said changes to bail and sentencing laws were long overdue: “Prison will never be a safe place for pregnant women and new mothers, and the government must change the law to stop their imprisonment.” The group has set up a petition in coalition with Women in Prison and Birth Companions.

An NHS spokesperson said: “The latest data shows rates of stillbirth overall have reduced by more than one fifth since 2013 – but any baby lost to a stillbirth is one too many. In England, the NHS is continuing to take steps to reduce stillbirths and neonatal deaths as well as working to ensure pregnant women in secure environments receive high quality, safe care.”