Dr Denis Walsh, associate professor in midwifery at Nottingham University, said pain was a "rite of passage" which often helped regulate childbirth.
He said it helped strengthen a mother's bond with her baby, and prepared her for the responsibility of motherhood.
But an obstetrician said epidurals were an important option for some women.
Dr Walsh, who wrote on the subject in the journal Evidence Based Midwifery, agreed that in some cases epidurals were very useful.
But he said epidural rates had been rising over the last 20 years, despite the fact that alternative, less invasive ways to manage pain in labour were available.
He said pain in labour was known to have positive physiological effects, such as helping to establish a rhythm to childbirth.
It also triggered the release of endorphins which helped women to adjust to pain.
Dr Walsh said epidurals were known to increase the risk that hormone treatment would be needed to boost contractions, and that devices such as forceps would be needed to complete the birth successfully.
He said: "I am concerned that if we increase epidural rates we do not know the long-term impacts of that."
But he warned that a culture had emerged where most hospitals effectively offered women epidurals on demand.
Official figures show the number of mothers receiving an epidural rose from 17% in 1989 to 1990 to 33% in 2007 to 2008.
Dr Walsh said the NHS should encourage alternative ways to deal with pain such as yoga, hypnosis, massage and birthing pools.