Epidurals don't slow down labour, according to new study

Epidurals don't slow labour according to a new study.
Epidurals don't slow labour according to a new study. Photo: shutterstock

Contrary to long-held assumptions, epidurals do not slow down labour. That's according to a new study exploring the impact of receiving pain-relief, compared to a placebo, on the duration of active labour in expectant mums.

The research, published in the journal Obstetrics & Gynecologyalso found that having an epidural had no impact on the rate of "normal vaginal delivery", whether an episiotomy was required, or the position of the baby at birth.

"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 of Harvard Medical School. "Not even the pain scores were statistically different between groups." As expected, however, pain scores for women who received a placebo, instead of the epidural, increased over time. 

According to the authors, obstetricians often reduce or discontinue epidural pain management during the second stage of labour, although this varies between hospitals. At the Chinese hospital in which the study took place, the team estimates that it occurs in around two-thirds of births.

But is this an outdated practice? Hess and his team set out to examine this question, recruiting 400 pregnant women, all of whom had requested epidural medication.

All mums-to-be in the study, received an epidural during the first stage of labour (when the cervix starts to soften and to dilate). When women entered the second stage of labour (when the cervix is fully dilated) they were randomly divided into two groups of 200. The first group received a top up of the epidural medication while the second received a placebo - an infusion of saline. All were healthy first-time mums with singelton pregnancies.

The study was double-blind, which means no one, including the mothers, midwives, obstetricians, or researchers knew whether mums had received the epidural or the saline. Additionally, mums experiencing "excessive pain" were able to request an epidural - and doctors were able to stop epidural infusions if required.

According to the authors, "Maintaining the infusion of epidural medication had no effect on the duration of the second stage of labor compared with a placebo infusion." Women who had an epidural experienced a second stage of labour of around 52 minutes, compared to around 51 minutes in those who received the placebo.

The spontaneous vaginal delivery rate was also similar between the groups, with 95.5 per cent of those who received an epidural, compared to 99 per cent in the placebo group. The team found no negative effects on other measures of bubs' health and well-being, including birth weight and Apgar scores.

There was one key - and unsurprising difference - between the two groups, however.

"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."

But while Hess reiterates that their team didn't observe any negative effects on mums and bubs in their research, he notes that epidural analgesia in the second stage of labour remains controversial and "merits follow up studies".