A new study suggests epidurals do not slow labour - meaning many women man have had their pain relief reduced unnecessarily due to an out-of-date practice.
There is a long-held belief that epidurals - a type of local anaesthetic - slow the second stage of labour.
But a new study, published in the journal Obstetrics & Gynecology, finds that epidural has no effect on duration of second stage of labour compared with a placebo.
The study included 400 healthy first-time mothers.
"We found that exchanging the epidural anaesthetic with a saline placebo made no difference in the duration of the second stage of labour," said senior author Philip Hess, associate professor of anaesthesia and obstetrics at Harvard Medical School and director of obstetric anaesthesia at the Beth Israel Deaconess Medical Center.
"Not even the pain scores were statistically different between groups. However, pain scores in women receiving the saline placebo increased over time, as would be expected."
An epidural is an injection in the back to stop you feeling pain in part of your body.