The hidden risks of epidurals: a common intervention, epidurals are given to reduce pain during birth. But at what cost? A leading Australian physician discusses how this invasive procedure actually impedes labor--and harms both mother and baby.

Publication: Mothering

Publication Date: 01-NOV-05

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COPYRIGHT 2005 Mothering Magazine

THE FIRST RECORDED USE of an epidural was in 1885, when New York neurologist J. Leonard Corning injected cocaine into the back of a patient suffering from "spinal weakness and seminal incontinence." (1) More than a century later, epidurals have become the most popular method of analgesia, or pain relief, in US birth rooms. In 2002, almost two-thirds of laboring women, including 59 percent of women who had a vaginal birth, reported that they were administered an epidural. (2) In Canada in 2001-2002, around half of women who birthed vaginally used an epidural, (3) and in the UK in 2003-2004, 21 percent of women had an epidural before or during delivery. (4)

Epidurals involve the injection of a local anesthetic drug (derived from cocaine) into the epidural space--the space around (epi) the tough coverings (dura) that protect the spinal cord. A conventional epidural will numb or block both the sensory and motor nerves as they exit from the spinal cord, giving very effective pain relief for labor but making the recipient unable to move the lower part of her body. In the last five to ten years, epidurals have been developed with lower concentrations of local anesthetic drugs, and with combinations of local anesthetics and opiate painkillers (drugs similar to morphine and meperidine) to reduce the motor block. They produce a so-called walking epidural.

Spinal analgesia has also been increasingly used in labor to reduce the motor block. Spinals involve drugs injected right through the dura and into the spinal (intrathecal) space, and they produce only short-term analgesia. To prolong the pain-relieving effect for labor, epidurals are now being coadministered with spinals, as a combined spinal epidural (CSE).

Epidurals and spinals offer laboring women the most effective form of pain relief available, and women who have used these analgesics rate their satisfaction with pain relief as very high. However, satisfaction with pain relief does not equate with overall satisfaction with birth, (5) and epidurals are associated with major disruptions to the processes of birth. These disruptions can interfere with a woman's ultimate enjoyment of and satisfaction with her labor experience, and they may also compromise the safety of birth for the mother and baby.

epidurals and labor hormones

Epidurals significantly interfere with some of the major hormones of labor and birth, which may explain their negative effect on the processes of labor. (6) As the World Health Organization comments, "epidural analgesia is one of the most striking examples of the medicalization of normal birth, transforming a physiological event into a medical procedure." (7)

For example, oxytocin, known as the hormone of love, is also a natural uterotonic--a substance that causes a woman's uterus to contract in labor. Epidurals lower the mother's release of oxytocin (8) or stop its normal rise during labor. (9) The effect of spinals on oxytocin release is even more marked. (10) Epidurals also obliterate the maternal oxytocin peak that occurs at birth (11)--the highest of a mother's lifetime--which catalyzes the final powerful contractions of labor and helps mother and baby fall in love at first meeting. Another important uterotonic hormone, prostaglandin F2 alpha, is also reduced in women using an epidural. (12)

Beta-endorphin is the stress hormone that builds up in a natural labor to help the laboring woman transcend pain. Beta-endorphin is also associated with the altered state of consciousness that is normal in labor. Being "on another planet," as some describe it, helps the mother-to-be to work instinctively with her body and her baby, often using movement and sounds. Epidurals reduce the laboring woman's release of beta-endorphin. (13, 14) Perhaps the widespread use of epidurals reflects our difficulty with supporting women in this altered state, and our cultural preference for laboring women to be quiet and acquiescent.

Adrenaline and noradrenaline (epinephrine and norepinephrine, collectively known as catecholamines, or CAs) are also released under stressful conditions, and levels naturally increase during an unmedicated labor. (15) At the end of an undisturbed labor, a natural surge in these hormones gives the mother the energy to push her baby out and makes her excited and fully alert at first meeting with her baby. This surge is known as the fetal ejection reflex. (16)

However, labor is inhibited by very high CA levels, which may result when the laboring woman feels hungry, cold, fearful, or unsafe. (17) This response makes evolutionary sense: If the mother senses danger, her hormones will slow or stop labor and give her time to flee to find a safer place to birth.

Epidurals reduce the laboring woman's release of CAs, which may be helpful if high levels are inhibiting her labor. However, a reduction in the final CA surge may contribute to the difficulty that women laboring with an epidural can experience in pushing out their babies, and to the increased risk of instrumental delivery (forceps and vacuum) that accompanies the use of an epidural (see below).

effects on the process of labor

Epidurals slow labor, possibly through the above effects on the laboring woman's oxytocin release, although there is also evidence from animal research that the local anesthetics used in epidurals may inhibit contractions by directly affecting the muscle of the uterus. (18)

On average, the first stage of labor is 26 minutes longer in women who use an epidural, and the second, pushing stage is is minutes longer. (19) Loss of the final oxytocin peak probably also contributes to the doubled risk of an instrumental delivery--vacuum or forceps--for women who use an epidural, (20) although other mechanisms may be involved.

For example, an epidural also numbs the laboring woman's pelvic floor muscles, which are important in guiding her baby's head into a good position for birth. When an epidural is in place, the baby is four times more likely to be persistently posterior (POP, or face up) in the final stages of labor--13 percent compared to 3 percent for women without an epidural, according to one study. (21) A POP position decreases the chance of a spontaneous vaginal delivery (SVD); in one study, only 26 percent of first-time mothers (and 57 percent of experienced...

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