Study: Epidurals Don’t Slow Labour, As Earlier Believed


Oct 20, 2017


Epidural analgesia, commonly called an epidural, is a mix of anesthetics and narcotics delivered by catheter near the nerves of the spine. It’s the most effective method of labour pain relief that we currently have.

Across the world, and certainly across India, hospitals vary in their rules regarding when during childbirth women can avail of epidural pain relief. In some places, epidurals are administered at any point during labour. But in others, there is such a thing as asking for pain relief “too late” for an epidural (though the cut-off is seldom explained to women beforehand); it’s a prohibition medical staff may invoke based on the pervasive idea that epidurals slow the second, and most active, stage of labour, which, when prolonged, is associated with adverse outcomes.

The thing is, a new study suggests that idea and practice could be out-of-date and misguided.

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According to research led by scientists at Beth Israel Deaconess Medical Center (BIDMC) and published in the journal Obstetrics & Gynecology, epidural medication had no effect on the duration of the second stage of labor, normal vaginal delivery rate, incidence of episiotomy, the position of the fetus at birth or any other measure of fetal well-being the researchers investigated. The study compared the effects of catheter-infused, low-concentration epidural anesthetic to a catheter-infused saline placebo in this double-blinded, randomized trial of 400 women.

“We found that exchanging the epidural anesthetic with a saline placebo made no difference in the duration of the second stage of labor,” said senior author Philip E. Hess, MD, Director of Obstetric Anesthesia at BIDMC and Associate Professor of Anaesthesia and of Obstetrics at Harvard Medical School. “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.”

The study enrolled healthy, first-time mothers who were provided with a patient-controlled epidural analgesic pump in the first stage of labor. All mothers were given active pain medication during this early stage of labor.

When they reached the second stage of labor, participants were randomized to receive either the active anesthetic (low doses of the drugs ropivacaine and sufentanil) or the saline placebo.

The primary outcome, the duration of the second stage of labor, was similar between both groups: about 52 minutes for women given active pain medication versus about 51 minutes for women given the saline — just a 3.3% difference. The median times were also similar: 45 minutes for women on active pain medication versus 46 for those on saline. Obstetricians requested to stop epidural infusions in 38 patients because of poor progression of labor. Of these, 17 of the women were in the saline group, and 21 were in the active medication group.

In addition to the duration of the second stage of labor, Hess and his colleagues looked at a variety of outcomes measuring fetal health and well-being, such as birth weight, Apgar scores — a quick measure of fetal health taken minutes after birth — and umbilical artery pH, a metric for assessing fetal blood oxygen levels. The team also compared patient-reported pain scores and patient satisfaction with pain control measures.

“Twice as many women given the placebo reported lower satisfaction with their pain relief compared to those provided the anesthetic,” said Hess. “Ethically, if epidural medications result in a negative effect on the second stage of labor, one could argue that a mild increase in maternal pain could be balanced by a successful vaginal delivery. We didn’t see any negative effects, but epidural analgesia in the second stage of labor remains controversial and merits follow up studies.”

While the study doesn’t present a definitive argument against limitations on epidural relief, it should open the door to further study, and give pregnant women some evidence to present to hospitals who still limit their access to pain relief.



Written By Lila Sahija

Lila reports on health and science news for The Swaddle. She has loved biology ever since she dissected her first frog in eighth grade, and now has a keen interest in examining human behavior. She also loves animals and takes at least one adventure a year through rural India. Oh, and she bakes a mean German coffee cake.


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