Having an epidural to ease the pain of childbirth does not slow labour down, a new study has found.

The findings could encourage more women to ask for the injections, with many avoiding the pain relief, amid NHS warnings that it could slow delivery.

The new research on more than 400 first time mothers found the spinal analgesia had no effect on the time it takes for them to deliver their child.

Around one in three women in the UK are given an epidural, but many avoid them, amid fears it will slow their labour and increase the risk of complications.

Guidance from the National Institute of Health and Care Excellence suggests that the pain relief can slow down the second stage of labour, increasing the chance of a forceps birth. Some studies have suggested the injections, in common use since the 1970s, can add more than two hours to labour.

When women are given an epidural, the intensity of contractions is lessened.

Some say the numbness can prolong labour, because it is harder to tell if they are pushing effectively - increasing the risk of complacations.

The new study, from Beth Israel Deaconess Medical Centre (BIDMC), Boston, suggests guidance should be re-examined.