An epidural is a form of regional anesthesia used widely for pain management during childbirth, delivering a local anesthetic and often an opioid into the epidural space near the spinal cord. This procedure effectively blocks pain signals from the lower body, providing significant relief from contractions. While offering powerful pain reduction, a common concern is whether the epidural slows the overall progress of labor. The answer is nuanced: it does not stop labor, but evidence suggests it can affect the duration of both the first and second stages.
Epidurals and the First Stage of Labor
The first stage of labor is defined by cervical dilation, progressing from the onset of contractions until the cervix is fully open at 10 centimeters. This stage is divided into the latent phase, which is the slower, earlier part of dilation, and the active phase, which is typically faster and more consistent. The timing of epidural placement can influence the duration of this stage.
Administering an epidural in the latent phase (before 4 to 6 centimeters of dilation) may slightly prolong the first stage of labor. However, modern, lower-dose epidural solutions have minimized this effect, and some large studies find no significant difference in the length of the first stage, regardless of when the epidural was started. When a slowdown does occur, it is sometimes attributed to the anesthetic interfering with the release of the body’s natural oxytocin, a hormone that stimulates uterine contractions.
Blocking pain signals from the cervix and pelvic tissues can reduce the natural feedback loop that triggers oxytocin production. If contractions become weaker or less frequent due to this interference, medical support may be needed to maintain labor progression. This often involves the intravenous administration of synthetic oxytocin to augment the strength and frequency of the contractions. Conversely, by providing effective pain relief and allowing the mother to rest, the epidural can sometimes improve the efficiency of contractions, potentially preventing a slowdown caused by maternal exhaustion.
How Epidurals Affect the Pushing Stage
The second stage of labor begins when the cervix is fully dilated and ends with the birth of the baby. The use of an epidural is consistently associated with a longer duration of pushing time. Studies have found that for those with an epidural, the second stage can be prolonged by an average of 15 to 20 minutes, though for some it may be much longer. This prolongation is primarily linked to the epidural’s effect on sensation and muscle function in the lower body.
The anesthesia reduces the mother’s natural, reflexive urge to push by numbing the nerves in the pelvic floor and tissues. This makes it difficult to feel the exact location and intensity of contractions, which are the body’s natural cues for effective bearing down. Because the mother may not feel the strong, involuntary urge to push, the expulsion of the baby becomes a more conscious and directed effort, which can take more time.
To mitigate this, one technique is “laboring down,” or passive descent, where the mother rests after full dilation, allowing the uterus to push the baby lower without active maternal effort. Healthcare providers may also adjust the epidural dosage to a lower concentration toward the end of the first stage or during the second stage to allow for better sensation and muscle control. Despite the potential for a longer pushing stage, the epidural is not considered a reason to limit the normal duration of the second stage, as long as the mother and baby are doing well.
Interventions Associated with Epidural Use
The physiological effects of an epidural on labor progression lead to an increased likelihood of certain medical interventions. When the first stage of labor slows, the most common response is labor augmentation using synthetic oxytocin to maintain or accelerate the pace of dilation. This helps to counteract any reduction in natural contraction strength caused by the anesthesia.
In the second stage, prolonged pushing time and reduced sensation contribute to a higher rate of assisted vaginal delivery. If a mother is unable to push effectively or if the second stage exceeds a certain time limit, a physician may use tools like a vacuum extractor or obstetric forceps to help guide the baby through the birth canal. Research consistently shows a link between epidural use and a two- to threefold increase in the risk of requiring an instrumental delivery.
A common concern is whether an epidural increases the risk of a cesarean section. While the epidural is linked to a longer duration of labor and an increase in other interventions, the overall body of evidence suggests that it does not significantly increase the rate of cesarean delivery. Contemporary studies, particularly those using modern, low-concentration epidurals, have largely concluded that the choice to use an epidural does not independently raise the overall risk of needing a cesarean section.