When epidural analgesia was first commonly used for pain relief in laboring women in the 1970s, it was an infusion into the spinal cord of a relatively large dose of an anesthetic drug such as lidocaine. The effect blocked pain and all movement from the waist down.
Since the mid-1990s, epidurals have been reformulated to try to achieve what Dr. William Camann, head of obstetric anesthesiology at Brigham and Women's Hospital in Boston and co-author of "Easy Labor," calls ideal pain relief during labor: a mixture of drugs that blocks pain nerves while leaving the motor nerves responsible for movement mostly unaffected.
These "low-dose" infusion epidurals usually include small amounts of the anesthetic bupivacaine and the opioid fentanyl. Together, the two drugs block pain without removing the patient's ability to move her legs.
This drug combination is sometimes referred to as a 'walking' epidural, even though women in the U.S. are rarely allowed to get up and walk, to minimize the hospital's legal liability from a fall. "It's still beneficial, even if you don't walk, because it allows you to move your legs, sit up and help with pushing," Camann says.
Most hospitals offer a patient-controlled version of epidurals with a button that can deliver an extra dose of medicine.
In the last decade, research on these low-dose epidurals has concluded:
• They do not increase the likelihood of having a C-section.
• They do lengthen labor somewhat, but only by about 20% on average and only in the second, or pushing, stage of labor.
• Compared with the old-style epidural, they decrease the rate of forceps- and vacuum-assisted births, although these are still higher compared with women without an epidural. Though the numbers are hard to pin down, about one-third of women with a low-dose epidural will have an instrument-assisted birth.
• With or without inclusion of fentanyl, they do not interfere with breast-feeding success.
• There is no reason to wait until the cervix is dilated to a certain point before administering an epidural to a woman in active labor.
• The duration of an epidural does not increase the amount of medicine that reaches the mom's or baby's bloodstream.
Epidural practices differ among doctors and hospitals, so women should ask questions, both before and during labor, about what medicine is in the epidural, whether intravenous fluids will be given and whether any other medications will by administered by shot or intravenously.