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Epidurals: real risk for mother and baby
by Dr Sarah Buckly
 

There are several types of epidural used in Australian hospitals. In a conventional epidural, a dose of local anaesthetic is injected through the lower back into the epidural space, around the spinal cord. This numbs the nerves which bring sensation from the uterus and birth canal. Unfortunately, the local anaesthetic also numbs the nerves which control the pelvic muscles and legs, so with this type of epidural, a woman usually cannot move her legs and, unless the epidural has worn off, cannot push her baby out, in the second stage of labour.

More recent forms of epidurals use a lower dose of local anaesthetic, usually combined with an opiate, such as pethidine, morphine or fentanyl (sublimaze). With this low-dose or combination epidural, most women can move around with support; however the chance of a woman being able to give birth without forceps is still low4. Another form of epidural, popular in the US, is the CSE, or combined spinal-epidural, where a one-off dose of opiate, with or without local anaesthetic, is injected into the spinal space, very close to the end of the spinal cord. This gives pain relief for around 2 hours, and if further pain relief is needed, it is given as an epidural. These forms of "walking epidural" may seem advantageous, but being attached to a CTG machine to monitor the baby, and hooked up to a drip which is also a requirement when an epidural is in place, can make walking impossible.

Many women have a good experience with epidurals. Sometimes the relief from pain can allow a woman to rest and relax sufficiently to go on and have a good birth experience. However deciding to use an epidural for pain relief can also lead to a "cascade of intervention", where an otherwise normal birth becomes highly medicalised, and a woman feels that she loses her control and autonomy. Often the decision to accept an epidural is made without an awareness of these, and other, significant risks to both mother and baby.

Although the drugs used in epidurals are injected around the spinal cord, substantial amounts enter the mother's blood stream, and pass through the placenta into the baby's circulation. Most of the side effects of epidurals are due to these "systemic", or whole-body effects.

One of the most commonly recognised side effects is a drop in blood pressure. Up to one woman in 8 will have this side effect to some degree5, and for this reason, extra fluids are usually given through a drip to prevent problems. A drop in the mother's blood pressure will affect how much of her blood is pumped to the placenta, and can lead to less oxygen being available to the baby.

An epidural will often slow a woman's labour, and she is three times more likely to be given an oxytocin drip to speed things up6 7. The second stage of labour is particularly slowed, leading to a three times increased chance of forceps8. Women having their first baby are particularly affected; choosing an epidural can reduce their chance of a normal delivery to less than 50%9.

This slowing of labour is at least partly related to the effect of the epidural on a woman's pelvic floor muscles. These muscles guide the baby's head so that it enters the birth canal in the best position. When these muscles are not working, dystocia, or poor progress, may result, leading to the need for high forceps to turn the baby, or a caesarean section. Having an epidural doubles a woman's chance of having a caesarean section for dystocia10.

When forceps are used, or if there is a concern that the second stage is too long, a woman may be given an episiotomy, where the perineum, or tissues between the vaginal entrance and anus, are cut to enlarge the outlet and hurry the birth. Stitches are needed and it may be painful to sit until the episiotomy has healed, in 2 to 4 weeks.

As well as numbing the uterus, an epidural will numb the bladder, and a woman may not be able to pass urine, in which case she will be catheterised. This involves a tube being passed up from the urethra to drain the bladder, which can feel uncomfortable or embarrassing.

Other side effects of epidurals vary a little depending on the particular drugs used. Pruritis, or generalized itching of the skin, is common when opiate drugs are given. It may be more or less intense and affects at least ¼ of women11 12: morphine or diamorphine are most likely to cause this. Morphine also causes oral herpes in 15% of women13 .

All opiate drugs can cause nausea and vomiting, although this is less likely with an epidural (around 30%14) than when these drugs are given into the muscle or bloodstream, where larger doses are needed. Up to 1/3 of women with an epidural will experience shivering15, which is related to effects on the bodies heat- regulating system.

When an epidural has been in place for more than 5 hours, a woman's body temperature may begin to rise16. This will lead to an increase in both her own and her baby's heart rate, which is detectable on the CTG monitor. Fetal tachycardia, or fast heart rate can be a sign of distress, and the elevated temperature can also be a sign of infection such as chorioamnionitis, which affects the uterus and baby. This can lead to such interventions as caesarean section for possible distress or infection, or, at the least, investigations of the baby after birth such as blood and spinal fluid samples, and several days of separation, observation, and possibly antibiotics, until the results are available17.

Less common side effects for a woman having an epidural are; accidental puncture of the dura, or spinal cord coverings, which can cause a prolonged and sometimes severe headache (1 in 100)18 ongoing numb patches, which usually clear after 3 months(1 in 550)19; and weakness and loss of sensation in the areas affected by the epidural, (4-18 in 10,000) also usually resolving by 3 months20.

More serious but rare side effects include permanent nerve damage; convulsions and heart and breathing difficulties (1 in 20,000)21 and death attributable to epidural. (1 in 200,000)22 When opiates are used, a woman may experience difficulty in breathing which comes on 6 to 12 hours later23.

There is a noticeable lack of research and information about the effects of epidurals on babies24. Drugs used in epidurals can reach levels at least as high as those in the mother25, and because of the baby's immature liver, these drugs take a long time- sometimes days- to be cleared from the baby's body26. Although findings are not consistent, possible problems, such as rapid breathing in the first few hours27 and vulnerability to low blood sugar28 suggest that these drugs have measurable effects on the newborn baby.

As well as these effects, babies can suffer from the interventions associated with epidural use; for example babies born by caesarean section have a higher risk of breathing difficulties29. When monitoring of the heart rate by CTG is difficult, babies may have a small electrode screwed into their scalp, which may not only be unpleasant, but occasionally can lead to infection.

There are also suggestions that babies born after epidurals may have difficulties with breastfeeding30 31 which may be a drug effect, or may relate to more subtle changes. Studies suggest that epidurals interfere with the release of oxytocin32 which, as well as causing the let-down effect in breastfeeding, encourages bonding between a mother and her young33.

Epidural research, much of it conducted by the anaesthetists who administer epidurals, has unfortunately focussed more on the pro's and con's of different drug combinations than on possible serious side-effects34. There have been, for example, no rigorous studies showing whether epidurals affect the successful establishment of breastfeeding35.

Several studies have found subtle but definite changes in the behaviour of newborn babies after epidural36 37 38 with one study showing that behavioural abnormalities persisted for at least six weeks39. Other studies have shown that, after an epidural, mothers spent less time with their newborn babies40, and described their babies at one month as more difficult to care for41.

While an epidural is certainly the most effective form of pain relief available, it is worth considering that ultimate satisfaction with the experience of giving birth may not be related to lack of pain. In fact, a UK survey which asked about satisfaction a year after the birth found that despite having the lowest self-rating for pain in labour (29 points out of 100), women who had given birth with an epidural were the most likely to be dissatisfied with their experience a year later42.

Some of this dissatisfaction was linked to long labours and forceps births, both of which may be a consequence of having an epidural. Women who had no pain relief reported the most pain (70 points out of 100) but had high rates of satisfaction.

Pain in childbirth is real, but epidural pain relief may not be the best solution. Talk about other options with your care-givers and friends. With good support, and the use of movement, breathing and sound, most women can give themselves, and their babies, the gift of a birth without drugs.

References

Sarah Buckley is a NZ-trained GP, and a published writer and advocate for gentle choices in pregnancy, birth and parenting. Sarah lives in Brisbane with her husband Nicholas, and is mother to Emma (12), Zoe (9), Jacob (7) and Maia Rose (2), all born naturally at home.