Whether an epidural slows down labor is a major concern for expectant parents considering pain management options during childbirth. Epidural analgesia is one of the most effective methods for pain relief, but its effect on the labor timeline has been debated for decades. Advances in medical protocols and medication have changed the answer significantly. Understanding the precise mechanism and how it interacts with the different stages of labor is necessary. While the overall process often involves minimal changes, the possibility of a longer second stage remains a topic of clinical discussion.
The Mechanism of Epidural Analgesia
An epidural provides pain relief by delivering a combination of local anesthetic and opioid medication directly into the epidural space, located just outside the membrane protecting the spinal cord and nerves. This medication bathes the spinal nerve roots, blocking the transmission of pain signals from the uterus and birth canal to the brain. Modern obstetric practice uses low-concentration solutions, such as bupivacaine, often combined with a low dose of opioid. This strategy achieves sensory block for pain relief while minimizing the motor block, which is the loss of muscle control. Limiting the motor block ensures the uterus’s ability to contract remains largely unaffected, providing comfort without paralyzing the muscles needed for effective pushing.
Epidurals and the First Stage of Labor
The first stage of labor involves the cervix dilating from zero to ten centimeters, divided into a latent phase and an active phase. Historically, administering an epidural during the latent phase (before about six centimeters of dilation) was thought to significantly slow labor progression. Studies show that while an epidural may extend the first stage, this prolongation is often minor, estimated at approximately 30 minutes. For the active phase of labor, which begins at six centimeters of cervical dilation, the effect is even less pronounced. The epidural has a minimal or clinically insignificant impact on the rate of cervical dilation, and research shows no increased risk of a cesarean delivery.
Epidurals and the Second Stage of Labor
The second stage of labor begins when the cervix is fully dilated and ends with the baby’s birth, involving the pushing phase. This stage is where the effect of the epidural on labor duration is most often observed. A Cochrane review found that, on average, the second stage may be extended by about 15 minutes for those who receive an epidural. The prolongation is attributed to reduced sensation, which can lessen the urge to push, and the slight motor block interfering with voluntary pushing muscles. Because of this, clinical guidelines allow for a longer duration for the second stage for individuals with an epidural, such as up to three hours for a first-time parent compared to two hours without.
Laboring Down
To mitigate the slowing effect on the second stage, “laboring down” is a common technique used with an epidural. This involves a period of passive fetal descent after full dilation, where the patient waits for the baby to descend further into the birth canal before beginning active pushing. This approach helps conserve the birthing person’s energy and improves the effectiveness of subsequent pushing efforts.
Addressing Potential Labor Interventions
When labor progress slows down, medical interventions may be used to help the process along. If contractions become inadequate after an epidural is placed, synthetic oxytocin (Pitocin) may be administered intravenously to strengthen the frequency and force of uterine contractions. If the second stage is significantly prolonged or if there are concerns about the baby’s well-being, an assisted vaginal delivery may be recommended. This involves using instruments, such as a vacuum extractor or forceps, to help guide the baby through the birth canal. Epidural use has been linked to a higher rate of assisted vaginal delivery, although newer, lower-dose protocols have reduced this association.