Epidurals are a popular form of pain control for women during labour, but they've long been blamed for hindering progress in the delivery room.
However, new research challenges this widely held belief, suggesting that epidurals have no effect on how long labour lasts.
"We found that exchanging the epidural anaesthetic with a saline placebo made no difference in the duration of the second stage of labour," said study lead researcher Dr Philip Hess. He directs obstetric anaesthesia at Beth Israel Deaconess Medical Center in Boston.
What exactly is an epidural?
Epidurals involve a combination of strong painkillers and anaesthetics delivered through a tube placed near the nerves of the spine. But since their introduction in the 1970s, epidurals have been thought by some to slow labour once the cervix is completely dilated – a period known as the second stage of labour.
When this stage of labour is prolonged and the birth of a baby is delayed, the risk for complications also rises. Some doctors may reduce or cease epidural pain management to try speed up delivery.
Why would it prolong labour?
But do epidurals really prolong labour? Wu said that sometimes it can seem that way to patients.
"Patients often cite longer pushing as a reason they are trying to avoid epidural," she explained. "The difficulty for these patients is that there may be many hours of contractions before they even get to the second stage or the 'pushing' stage. So, when patients are too numb to push effectively, doctors often cite this as a reason to turn down epidural."
More pain = more discomfort
But reductions in epidural pain relief can mean more discomfort for the woman, Wu noted. It's a "delicate balance", she said.
In the new study, the Boston team compared the effects of low-dose epidural to an ineffective saline solution placebo, both of which were delivered through a catheter.
The study involved 400 healthy women delivering their first baby. They received epidurals during the early stage of labour. But once they reached the second stage, they were randomly assigned to receive either the epidural or the placebo, Hess explained.
The study was double-blinded, meaning that neither the women nor the doctors knew whether they received the epidural or the saline solution.
Painkillers and anaesthetics are delivered through a tube near the nerves of the spine.
During the study, the researchers tracked the duration of labour as well as the health and well-being of the women's babies, such as birth weight and blood oxygen levels. The investigators also compared the women's reports of pain and satisfaction with their pain management.
The study, published in Obstetrics & Gynecology, found epidurals had no effect on the duration of the second stage of labour. The anaesthesia also had no impact on the rate of normal vaginal deliveries, the number of episiotomies [surgical cuts to ease delivery], the position of the foetus at birth or any other measure used to assess the well-being of a baby during delivery.
The duration and outcomes of labour were similar for both groups of women. The second stage of labour was about 52 minutes for women given active pain medication compared to about 51 minutes for women who received saline, the research team noted.
A tough balance
On the other hand, "twice as many women given the placebo reported lower satisfaction with their pain relief compared to those provided the [epidural] anaesthetic," Hess said.
Dr Mitchell Kramer is chair of obstetrics and gynaecology at Huntington Hospital in Huntington, New York. Reviewing the new study, he said its findings are in line with those of prior studies. But he also agreed with Wu that it's often tough to balance pain relief with the need to avoid numbness during labour.
"If there is significant pain block, whereby the patient cannot feel contractions at all or cannot move their legs to assist in the pushing process during the second stage of labour, this may pose a problem during this stage," Kramer explained.
According to Kramer, the Boston study shows that epidurals are largely beneficial, so "we can reassure our patients that we can keep them comfortable and yet not jeopardise or prolong the labour".
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