The study by Bath's Royal United Hospital, looked at the complications from the 700, 000 epidural injections given every year, and found the risk of harm was as low as one in 23,000-ten times less than has been estimated.

Findings from the research also concluded that expectant mothers in particular shouldn't be overly concerned, as risk of permanent harm for them is as little as one in 80,000.

Dr Tim Cook, lead researcher and consultant anesthetist said of the findings: "The results are reassuring for patients.

The procedure, given into the small of a patient's back is an effective form of pain relief, commonly used during labour.

The team at Bath were given data from all hospitals in the UK, finding that only between 14 and 30 patients were permanently harmed from the spinal anesthetic.