Women in labour are being refused epidurals in breach of official guidelines, a government inquiry has found.

In findings seen by the Guardian, an investigation by the Department of Health and Social Care also found that women may not be being kept fully informed that if they choose to give birth at home or in a midwife-led unit they may have to be transferred if they want an epidural. Failing to make women aware of that possibility would also be in breach of National Institute for Health and Care Excellence (Nice) guidelines.

As a result of the inquiry, the health minister Nadine Dorries will write to all heads and directors of midwifery and medical directors at NHS trusts this week to remind them of the Nice guidance regarding pain relief during childbirth and to ensure it is being followed.

Clare Murphy, director of external affairs at the British Pregnancy Advisory Service, said the “results of the government’s inquiry are sadly not surprising”.

She added: “We have spoken with many women who have been so traumatised by their experience of childbirth that they are considering ending what would otherwise be wanted pregnancies.

“Pain relief is sometimes treated as a ‘nice extra’ rather than an integral part of maternity care, and women and their families can suffer profoundly as a result.

“Staffing shortages may be an issue but we also know women may experience gatekeeping by healthcare professionals and be told labour ‘is meant to be hard work’,” she added.

Maureen Treadwell, from the Birth Trauma Association also welcomed the findings: “We are delighted, at long last, that the Department for Health and Social Care is looking seriously at this issue. Inadequate epidural services and misinformation about risks is simply inexcusable. It is both inhumane and discriminatory.”

Epidural blocks are a pain-relieving spinal injection that must be given by an anaesthetist in an obstetric unit. They are effective but not risk-free. Among other risks, they can lead to a drop in blood pressure.

NHS guidelines say that women in labour can ask for epidurals at any time, including during the early stage of labour, and should be given information and support to choose what is right for them.

But in January, a Sunday Telegraph investigation claimed some women were being denied epidurals because of what the paper said was a “cult of natural childbirth” in some NHS Trusts.

Dr David Bogod, a council member of the Royal College of Anaesthetists and a consultant at Nottingham University Hospitals NHS trust with a special interest in obstetrics, said midwives sometimes wrongly told women there was a narrow window in which they could have an epidural: when the cervix is between 4cm and 6cm dilated. “But it’s never too early and never too late [for an epidural], if that’s what a woman wants,” he said.

Bogod said that “there’s reasonable, anecdotal evidence that some midwives will use the excuse that an anaesthetist isn’t available if they themselves feel an epidural isn’t appropriate for the woman based on their own beliefs around intervention-free births”.

“The national standard is that a woman should be given an epidural within 30 minutes to one hour of asking for it, except in exceptional circumstances,” he said. “Labour wards are amply supplied with anaesthetists and so that isn’t an unreasonable target for us.

“The commonest reason for women to be denied an epidural is because of a lack in midwife numbers: we have a drastic national shortage of midwives,” he added. The NHS in England is short of the equivalent of almost 2,500 full-time midwives.

Bogod pointed to the scandals at Telford’s Princess Royal and the Royal Shrewsbury hospitals, and Morecambe Bay, where babies and mothers died preventable deaths at least partly because midwives had a focus on making women giving birth without medical intervention.

“I’m not saying it’s common or regular but there are anecdotal cases,” he said. “But it’s completely unacceptable.”

Gill Walton, chief executive of the Royal College of Midwives, (RCM) said: “Nice guidelines should be followed. Women should get pain relief when they ask. They should be making choices about their pain relief armed with the information they need to make an informed choice, so they get the pain relief that is right for them.”

Walton, however, said it was a lack of anaesthetists that sometimes led to delays in epidurals being administered. “Unfortunately, due to stretched resources anaesthetists are not always available, which poses real challenges for midwives seeking the best experience for women in labour,” she said.

A Care Quality Commission survey of women’s experiences of maternity care, published in January, found that epidural use in England has increased over the past three years from 28% to 31%.

But the survey also found that some women did not receive pain relief when they asked for it: 3% of women whose pain relief changed, reported that an anaesthetist was not available to provide their chosen pain relief and 4% responded that they were not told why they could not have their chosen pain relief.

The debate over medicalised births is long-running. RCM abandoned its normal birth campaign in 2017 amid concerns it may have put women at risk. But earlier this month University Hospitals Bristol NHS trust was criticised for advising pregnant women to avoid having epidurals. After the advice was reported in the media, the trust deleted the childbirth advice from its website and accepted it was “outdated”.

Pat O’Brien, a consultant in obstetrics and gynaecology at University College London hospitals and spokesperson for the Royal College of Obstetricians & Gynaecologists, said although there may still be pockets of midwives encouraging women to have non-medicalised births against their wishes, attitudes have changed “drastically” in the last few years.

“Ten years ago, you would often see it,” he said. “But there has been a real culture shift in the last few years.”