When to start epidural pain relief during labor and delivery should be up to the mother, researchers say.

Some earlier reports had suggested that starting epidural anesthesia early might prolong labor or increase the likelihood of a cesarean section - more commonly known as a C-section.

But a new formal review of past studies, published by The Cochrane Library, found that length of labor and the need for surgical intervention did not differ between women who received epidurals during early or later stages of labor.

“I think there are still providers that were trained in the earlier era, when they preferred their patients to receive an epidural in the later stages of labor,” said Dr. Neil Seligman.

Seligman, who was not involved in the new analysis, is a maternal and fetal medicine expert at University of Rochester Medical Center in New York.

"The literature has been fairly consistent that epidurals do not meaningfully prolong labor," he said. "There may be a small difference but there is no meaningful difference."

For the new analysis, researchers led by Dr. Ban Leong Sng of Singapore’s KK Women’s and Children’s Hospital reviewed clinical trials that randomly assigned about 16,000 women to receive epidurals during early or later stages of labor.

Epidural medications are delivered into a space near the spinal cord.

An epidural was considered "early" if the cervix (the lower part of the womb) was open no more than four to five centimeters (about two inches). "Later" epidurals were started when the cervix was open more widely.

There were no differences between the two groups in the need for C-sections or other interventions, such as forceps, during labor. There was also no difference in the length of the second or “pushing” stage of labor between the two groups.

“We conclude that it would appear to be advantageous to initiate epidural analgesia for labor early, when requested by the woman,” the researchers write.

They say the findings support the recommendation of the American College of Obstetricians and Gynecologists, which says a woman’s request for an epidural during labor should guide its use – unless there are other complications or concerns.

Ideally, Seligman said the conversation about epidurals and pain control during labor should start in the doctor's office before labor even begins.

"Even if the patient has no preconceptions, you can introduce the idea, 'Have you thought about how you’re going to control pain during labor?'" Seligman said.