New mothers are being charged up to £14,000 to give birth in England, according to a report on the experiences of migrant women who have been billed for NHS maternity services.

The report, published on Thursday by the healthcare charity Doctors of the World (DOTW), reveals that more than a third (37.8%) of the mothers surveyed – who include undocumented, refugee and asylum-seeking women – received a bill for maternity care after their babies were delivered, ranging from £296 to £14,000. Of that group, half were charged £7,000 or more.

The charity found that many had been charged incorrectly, as current rules stipulate migrant women should be charged at 150% of the cost of secondary care, but certain groups, including asylum seekers, refugees and those with leave to remain, are exempt under government legislation.

Anna Miller, of DOTW, said: “At our clinic we see women with a range of different immigration status who are charged for NHS maternity services and avoid antenatal care as a result.

“In some cases, these are women without formal status in the UK who are charged under the policy and will end up with large bills they are unable to pay. In other cases, it’s people who are eligible for free NHS maternity care, such as refugees and asylum seekers, who have been charged incorrectly.”

Kemi, 38, received a letter from her local NHS trust less than two weeks after her baby was born by emergency caesarean section, warning her she should pay £4,900 or risk being reported to the Home Office.

“As soon as I got that bill, the landlord made me and my baby leave the house,” Kemi said. “I became so depressed – I didn’t see myself as a human being any more.”

Unable to pay the bill for maternity care and having been evicted from her home, she began using food banks and sleeping rough with her baby.

Kemi arrived in the UK from Nigeria on a student visa and had applied for asylum by the time she gave birth in 2016. It took four years to prove that she did not have to pay the crippling charges, during which time she and her baby were homeless.

“Police cars would go past us and we had to hide, because I was so scared they were looking for me, wanting me to pay that bill,” she said. “I had to cover my baby’s head, and hide, because I didn’t want them to take her away from me.

“I was in so much pain because the wound [from the caesarean section] hadn’t healed properly and my baby was so cold, so malnourished. I had to feed her canned food,” she said.

According to DOTW, the cost of a vaginal delivery is typically between £5,000 and £7,000. Complications, such as instrumental delivery or caesarean section, incur higher costs. A debt of £500 unpaid after three months may be reported to the Home Office and owing a debt to the NHS can be grounds for refusing applications to remain in the UK.

Alongside postnatal debt, DOTW says the charging regulations are having a significant impact on women before they give birth, with some service users deterred from seeking healthcare because of the costs they may face.

The charity’s findings show that, while more than two-thirds (67.6%) of women nationally have had their first antenatal appointment by 10 weeks, only 19% of the women it surveyed had had their first antenatal care appointment by then.

These findings come after a review of ethnic inequalities in maternal healthcare, published by the NHS Race and Health Observatory in February, highlighted a lack of adequate interpreting services and other barriers to communication within maternity services, as well as disrespect, stereotyping and discrimination.

Dr Claire van Nispen tot Pannerden, one of the report’s authors, who has also led a mother and children’s clinic for DOTW, said: “We’re concerned that this is just the tip of the iceberg. We’re receiving more calls from women saying ‘I’ve received this letter, what do I do?’ From very early on in pregnancy, women are being targeted with these warnings.”

She added: “This is part of a much bigger hostile environment. We need to do much better at understanding the barriers these women are facing and we are urging an independent public inquiry and an end to the charging of maternity-care services.”

A government spokesperson said: “All refugees, asylum seekers and victims of modern slavery are exempt from NHS treatment costs. While some migrants or visitors to the UK may be required to contribute, we’ve always been clear that urgent care should never be delayed or withheld over charges, including all maternity services.”

• Reporting for this article was supported by a grant from the International Women’s Media Foundation’s Howard G Buffett fund for women journalists