A new study contradicts previous research that suggests epidurals can prevent women from feeling pain and therefore delay pushing during childbirth.

When epidurals began to enter mainstream clinical practice in the 1960s, it offered millions of women the unprecedented opportunity to opt for pain relief during the taxing experience of childbirth.

Today, epidurals, a type of anesthesia that blocks pain transmission in the pelvic region, are the centerpiece of pain management during labor and delivery.

Though routinely used in hospitals, controversy remains around whether epidurals directly impact labor.

In the past, several studies have found an association between epidural use and longer labor.

This is especially prevalent during the second stage, where women are actively pushing and giving birth.

These findings have left many obstetric practitioners hesitant to maintain an epidural as labor progresses.

The concern is that epidurals may blunt a woman’s ability to feel uterine contractions cuing her to push, therefore prolonging labor.

Lengthier labors are associated with complications such as infection of the fetal membranes as well as perineal tears and excessive bleeding after birth.

However, a recent study from Beth Israel Deaconess Medical Center (BIDMC) and Nanjing Maternity and Child Health Care Hospital may dispel this widely held belief.

Researchers say they found no evidence that epidurals actually cause a prolonged second stage of labor.

The strength of the study lies in its design, which utilizes a method called a randomized controlled trial (RCT).

RCTs are highly commended for their ability to identify whether a cause-and-effect relationship exists between two events.

Dr. Philip Hess, an anesthesiologist at BIDMC and co-author of this study, explains.

“Primarily, the older studies were observational studies, which gives you an association, but it doesn’t necessarily mean that there’s cause and effect,” he told Healthline.

In observational studies, scientists look at historical data and analyze whether two events were related to each other.

Even more, past research presented a classic “chicken or the egg” conundrum.

Were epidurals more likely to be used in difficult, longer, more painful labors, or were epidurals the precipitating factor for such a labor?

“Observational trials can’t answer that, only a randomized controlled trial can,” said Hess. “Observational trials can’t distinguish how much pain a woman was experiencing before requesting an epidural, or if the labor was difficult, or was a labor with dystocia —all circumstances where women are more likely to request an epidural. It explains why you would expect to see a longer or more difficult labor in women who choose to have epidural.”

In this study, 400 healthy women who carried their first pregnancies to term were split equally into two groups.

Initially, both groups of women received a low concentration of epidural medication during the first stage of labor, which lasts from onset of labor to when a woman is ready to push.

As the women progressed to the second stage, half remained on the epidural medication while the other half received a saline placebo.

Participants, obstetricians, and investigators weren’t aware of who continued to receive the medication and who received placebo.

Apart from labor duration, the study authors also didn’t observe an increased likelihood of intervention during delivery, such as the use of forceps, an episiotomy (a surgical cut between the vagina and anus), or a cesarean delivery.

Even more, after delivery, babies had similar health outcomes irrespective of epidural use.

While there were no significant differences between how women ranked their pain during labor, the study did find that maternal satisfaction for pain relief was lower in the placebo group than in the epidural group.

Dr. Joseph Wax, the chair of the American Congress of Obstetricians and Gynecologists (ACOG) Committee on Obstetric Practice, affirmed the findings, stating that its design “provides clarity.”

“The results suggest that epidurals do not significantly increase the duration of the second stage,” he told Healthline. “Providers and women should be reassured that the benefit of pain relief provided by epidurals in the second stage of labor does not come at the expense of a longer second stage.”

While the findings of the study are promising, Wax underscores that more research may be required before the practice can be widely applicable.

“The study was performed in a specific patient population in one hospital outside of the U.S. with a specific protocol for medicating the epidural, and it remains unclear as to whether these results are generalizable to all laboring women elsewhere,” he said.

The trial was conducted at BIDMC’s sister institution in Nanjing, China.

But according to Hess, obstetric practices at the hospital were comparable to those used at BIDMC, and at times, more advanced.

While Hess agrees that more research may be required, he is excited for the potential to positively impact clinical care for mothers in pain.

“The findings should be generalized,” he said. “From a mechanism point of view, there shouldn’t be any reason why people who are Asian would be different from Caucasian or African-Americans. Epidural medications work the same in all the races. We do not adjust medication doses based on that factor.”

For Hess, the main takeaway is that the choice to use an epidural during labor should solely be based on “pain and preference.”

“Using modern epidural techniques for pain relief has become much more safe, much more effective with fewer side effects,” he said. “Recent studies demonstrate that epidural medication doesn’t have a significant effect on labor, mom’s safety, or the baby’s. The decision to use an epidural shouldn’t include fears about how it will affect labor itself.”