By Mary Elizabeth Dallas
However, new research challenges this widely held belief, suggesting that epidurals have no effect on how long labor lasts -- or when babies are born.
"We found that exchanging the epidural anesthetic with a [non-drug] saline placebo made no difference in the duration of the second stage of labor," said study lead researcher Dr. Philip Hess. He directs obstetric anesthesia at Beth Israel Deaconess Medical Center in Boston.
Dr. Jennifer Wu, an ob/gyn who reviewed the new findings, said there are "important aspects to this study."
Use of "low-dose epidurals versus placebos during the pushing stage of labor did not increase duration of pushing" or the need for a C-section, said Wu, who works at Lenox Hill Hospital in New York City.
As the study authors explained, epidurals involve a combination of strong painkillers and anesthetics 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 labor once the cervix is completely dilated -- a period known as the second stage of labor.
When this stage of labor is prolonged and the birth of a baby is delayed, the risk for complications also rises. As a result, some doctors may reduce or cease epidural pain management in an attempt to speed up delivery.
But do epidurals really prolong labor? 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 -- and lack of sleep -- 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."
But, of course, 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. These first-time mothers received epidurals during the early stage of labor. 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. However, women in extreme, excessive pain were knowingly given pain medication as directed by their doctors. The doctors could also stop epidural pain control at any time.
During the study, the researchers tracked the duration of labor 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 Oct. 10 in Obstetrics & Gynecology, found epidurals had no effect on the duration of the second stage of labor. The anesthesia also had no impact on the rate of normal vaginal deliveries, the number of episiotomies [surgical cuts to ease delivery], the position of the fetus at birth or any other measure used to assess the well-being of a baby during delivery.
The duration and outcomes of labor were similar for both groups of women. The second stage of labor was about 52 minutes for women given active pain medication compared to about 51 minutes for women who received saline, the research team noted.
Citing slow progression of labor, doctors were requested to stop epidural pain control for 38 patients. But the researchers found that this occurred at about the same rate for women receiving the epidural as for women who received the saline.
On the other hand, "twice as many women given the placebo reported lower satisfaction with their pain relief compared to those provided the [epidural] anesthetic," Hess said.
Dr. Mitchell Kramer is chair of obstetrics and gynecology at Huntington Hospital in Huntington, N.Y. 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 labor.
"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 labor, this may pose a problem during this stage," Kramer explained.
"Frequently, the amount of anesthetic medication being infused will be decreased, not turned off, to allow some feeling and/or movement to assist in the pushing efforts," he said.
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 jeopardize or prolong the labor."