The health secretary, Matt Hancock, has promised to investigate allegations that some women are denied pain-relieving spinal injections during childbirth.

NHS guidelines say that women in labour can ask for pain relief at any time and should be given information and support to choose what is right for them. Epidural blocks, injected into the area around the spine, are highly effective, but they have to be given by an anaesthetist in an obstetric unit. They can lead to a drop in blood pressure in up to 14% of women, so close monitoring is important.

Some women claim that they are being denied epidurals because of what the Sunday Telegraph says is “a cult of natural childbirth” in six hospital trusts. Several claimed they were told they were either insufficiently dilated or too far dilated to have an epidural.

The trusts, which included Homerton university hospital trust in London, university hospitals of Leicester trust, Surrey and Sussex healthcare NHS trust and Western Sussex hospitals NHS foundation trust, all said they endeavoured to comply with guidelines from the National Institute for Health and Care Excellence and give pain relief in a timely manner.

Hancock said he would investigate the allegations. He said in a statement: “I want all expectant mothers to be able to make an informed choice that’s right for them, to know this choice will be fully respected and to have the freedom to change their mind.

“Clinical guidance clearly states that you can ask for pain relief at any time – before and during labour – and as long as it is safe to do so this should never be refused. I’m concerned by evidence that such requests are being denied for anything other than a clinical reason.

“It’s vital this guidance is being followed right across the NHS, as part of making it the best place in the world to give birth. Women being denied pain relief is wrong, and we will be investigating.”