The Hidden Risk 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. Adapted from the book Gentle Birth, Gentle Mothering; The wisdom and science of gentle choices in pregnancy, birth, and parenting available from www.sarahjbuckley.com

By Sarah J. Buckley

diagram of epidural injectionThe 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”hthe 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”ha substance that causes a woman’s uterus to contract in labor. Epidurals lower the mother’s release of oxytocin8 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 birth11“hthe highest of a mother’s lifetime”hwhich 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 15 minutes longer.19 Loss of the final oxytocin peak probably also contributes to the doubled risk of an instrumental delivery”hvacuum or forceps”hfor 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”h13 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 mothers) with POP babies experienced an SVD; the remaining mothers had an instrumental birth (forceps or vacuum) or a cesarean.22

Anesthetists have hoped that a low-dose or combined spinal epidural would reduce the chances of an instrumental delivery, but the improvement seems to be modest. In one study, the Comparative Obstetric Mobile Epidural Trial (COMET), 37 percent of women with a conventional epidural experienced instrumental births, compared with 29 percent of women using low-dose epidurals and 28 percent of women using combined spinal epidurals.23

For the baby, instrumental delivery can increase the short-term risks of bruising, facial injury, displacement of the skull bones, and cephalohematoma (blood clot under the scalp).24 The risk of intracranial hemorrhage (bleeding inside the brain) was increased in one study by more than four times for babies born by forceps compared to those with spontaneous births,25 although two studies showed no detectable developmental differences for forceps-born children at five years old.26, 27 Another study showed that when women with an epidural had a forceps delivery, the force used by the clinician to deliver the baby was almost twice the force used when an epidural was not in place.28

Epidurals also increase the need for Pitocin to augment labor, probably due to the negative effect on the laboring woman’s own release of oxytocin. Women laboring with an epidural in place are almost three times more likely to be administered Pitocin.29 The combination of epidurals and Pitocin, both of which can cause abnormalities in the fetal heart rate (FHR) that indicate fetal distress, markedly increases the risk of operative delivery (forceps, vacuum, or cesarean delivery). In one Australian survey, about half of first-time mothers who were administered both an epidural and Pitocin had an operative delivery.30

The impact of epidurals on the risk of cesarean is contentious; differing recent reviews suggest no increased risk31 and an increase in risk of 50 percent.32 The risk is probably most significant for women having an epidural with their first baby.33

Note that the studies used to arrive at these conclusions are mostly randomized controlled trials in which the women who agree to participate are randomly assigned to either epidural or nonepidural pain relief. Nonepidural pain relief usually involves the administration of opiates such as meperidine (aka pethidine). Many of these studies are flawed from high rates of crossover”hwomen who were assigned to nonepidurals but who ultimately did have epidurals, and vice versa. Also, noting that there are no true controls”hthat is, women who are not using any form of pain relief”hthese studies cannot tell us anything about the impact of epidurals compared to birth without analgesic drugs.

Epidural Techniques and Side Effects
The drugs used in labor epidurals are powerful enough to numb, and usually paralyze, the mother’s lower body, so it is not surprising that there can be significant side effects for mother and baby. These side effects range from minor to life-threatening and depend, to some extent, on the specific drugs used.

Many of the epidural side effects mentioned below are not improved with low-dose or walking epidurals, because women using these techniques may still receive a substantial total dose of local anesthetic, especially when continuous infusions and/or patient-controlled boluses (single large doses) are used.34 The addition of opiate drugs in epidurals or CSEs can create further risks for the mother, such as pruritus (itching) and respiratory depression (see below).

Maternal Side Effects
The most common side effect of epidurals is a drop in blood pressure. This effect is almost universal and is usually preempted by administering IV fluids before placing an epidural. Even with this “preloading” episodes of significant low blood pressure (hypotension) occur for up to half of all women laboring with an epidural,35, 36 especially in the minutes following the administration of a drug bolus. Hypotension can cause complications ranging from feeling faint to cardiac arrest37 and can also affect the baby’s blood supply (see below). Hypotension can be treated with more IV fluids and, if severe, with injections of epinephrine (adrenaline).

Other common side effects of epidurals include inability to pass urine (necessitating a urinary catheter) for up to two-thirds of women;38 itching of the skin (pruritus) for up to two-thirds of women administered an opiate drug via epidural;39, 40 shivering for up to one in three women;41 sedation for around one in five women;42 and nausea and vomiting for one in twenty women.43

Epidurals can also cause a rise in temperature in laboring women. Fever over 100.4 F (38 C) during labor is five times more likely overall for women using an epidural;44 this rise in temperature is more common in women having their first babies, and more marked with prolonged exposure to epidurals.45 For example, in one study, 7 percent of first-time mothers laboring with an epidural were feverish after six hours, increasing to 36 percent after 18 hours.46 Maternal fever can have a significant effect on the baby (see below).

Opiate drugs, especially administered as spinals, can cause unexpected breathing difficulties for the mother, which may come on hours after birth and may progress to respiratory arrest. One author comments, “Respiratory depression remains one of the most feared and least predictable complications of intrathecal [spinal] opioids.”47

Many observational studies have found an association between epidural use and bleeding after birth (postpartum hemorrhage).48-53 For example, a large UK study found that women were twice as likely to experience postpartum hemorrhaging when they used an epidural in labor.54 This statistic may be related to the increase in instrumental births and perineal trauma (causing bleeding), or may reflect some of the hormonal disruptions mentioned above.

An epidural gives inadequate pain relief for 10 to 15 percent of women,55 and the epidural catheter needs to be reinserted in about 5 percent.56 For around 1 percent of women, the epidural needle punctures the dura (dural tap); this usually causes a severe headache that can last up to six weeks, but can usually be treated by an injection into the epidural space.57, 58

More serious side effects are rare. If epidural drugs are inadvertently injected into the bloodstream, local anesthetics can cause toxic effects such as slurred speech, drowsiness, and, at high doses, convulsions. This error occurs in around one in 2,800 epidural insertions.59 Overall, life-threatening reactions occur for around one in 4,000 women.60-63 Death associated with an obstetric epidural is very rare,64 but it can be caused by cardiac or respiratory arrest, or by an epidural abscess that develops days or weeks afterward.

Later complications include weakness and numbness in 4 to 18 per 10,000 women. Most of these complications resolve spontaneously within three months.65-69 Longer-term or permanent problems can arise from damage to a nerve during epidural placement; from abscess or hematoma (blood clot), which can compress the spinal cord; and from toxic reactions in the covering of the spinal cord, which can lead to paraplegia.70

Side Effects for the Baby
Some of the most significant and well-documented side effects for the unborn baby (fetus) and newborn derive from effects on the mother. These include, as mentioned above, effects on her hormonal orchestration, blood pressure, and temperature regulation. As well, drug levels in the fetus and newborn may be even higher than in the mother,71 which may cause direct toxic effects. For example, epidurals can cause changes in the fetal heart rate (FHR) that indicate that the unborn baby is lacking blood and oxygen. This effect is well known to occur soon after the administration of an epidural (usually within the first 30 minutes), can last for 20 minutes, and is particularly likely following the use of opiate drugs administered via epidural and spinal. Most of these changes in FHR will resolve themselves spontaneously with a change in position. More rarely, they may require drug treatment.72 More severe changes, and the fetal distress they reflect, may require an urgent cesarean.

Note also that the use of opiate drugs for labor analgesia can also cause FHR abnormalities. This process makes the real effects of epidurals on FHR hard to assess because, in almost all randomized trials, epidurals are compared with meperidine or other opiate drugs. One researcher notes that the supine position (lying on the back) may contribute significantly to hypotension and FHR abnormalities when an epidural is in place.73 Another found that the supine position (plus epidural) was associated with a significant decrease in the oxygen supply to the baby’s brain (fetal cerebral oxygenation).74

The baby can also be affected by an epidural-induced rise in the laboring mother’s temperature. In one large study of first-time mothers, babies born to febrile (feverish) mothers, 97 percent of whom had received epidurals, were more likely than babies born to afebrile mothers to be in poor condition (low Apgar score); have poor tone; require resuscitation (11.5 percent versus 3 percent); or have seizures in the newborn period.75 One researcher noted a tenfold increase in risk of newborn encephalopathy (signs of brain damage) in babies born to febrile mothers.76

Maternal fever in labor can also directly cause problems for the newborn. Because fever can be a sign of infection involving the uterus, babies born to febrile mothers are almost always evaluated for infection (sepsis). Sepsis evaluation involves prolonged separation from the mother, admission to special care, invasive tests, and, most likely, administration of antibiotics until test results are available. In one study of first-time mothers, 34 percent of epidural babies were given a sepsis evaluation compared to 9.8 percent of nonepidural babies.77

Drugs and Toxicity
Every drug that the mother receives in labor will pass through the placenta to her baby, who is more vulnerable to toxic effects. The maximum effects are likely to be at birth and in the hours immediately after, when drug levels are highest.

There are few studies of the condition of epidural babies at birth, and almost all of these compare babies born after epidurals with babies born after exposure to opiate drugs, which are known to cause drowsiness and difficulty with breathing. These studies show little difference between epidural and nonepidural (usually opiate-exposed) babies in terms of Apgar score and umbilical-cord pH, both of which reflect a baby’s condition at birth.78 However, a large-population survey from Sweden found that use of an epidural was significantly associated with a low Apgar score at birth.79

There are also reports of newborn drug toxicity from epidural drugs, especially opiates administered via epidural.80 Newborn opiate toxicity seems more likely with higher dose regimes, including those where the mother is able to self-administer extra doses, although there are wide differences in individual newborn sensitivity.81

It is important to note that a newborn baby’s ability to process and excrete drugs is much less than an adult’s. For example, the half-life (time to reduce drug blood levels by half) for the local anesthetic bupivacaine (Marcaine) is 8.1 hours in the newborn, compared to 2.7 hours in the mother.82 Also, drug blood levels may not accurately reflect the baby’s toxic load because drugs may be taken up from the blood and stored in newborn tissues such as the brain and liver,83 from where they are more slowly released.84

A recent review also found higher rates of jaundice for epidural-exposed babies. This result may be related to the increase in instrumental deliveries or to the increased use of Pitocin.85

Neurobehavioral Effects
The effects of epidural drugs on newborn neurobehavior (behavior that reflects brain state) are controversial. Older studies comparing babies exposed to epidurals with babies whose mothers received no drugs have found significant neurobehavioral effects, whereas more recent findings from randomized controlled trials (which, as noted, compare epidural- and opiate-exposed newborns) have found no differences. However, these older studies also used the more comprehensive (and difficult to administer) Brazelton Neonatal Behavioral Assessment Score (NBAS, devised by pediatricians), whereas more recent tests have used less complex procedures, especially the Neurologic and Adaptive Capacity Score (NACS, devised by anesthesiologists), which aggregates all data into a single figure and which has been criticized as insensitive and unreliable.86-88

For example, all three studies comparing epidural-exposed with unmedicated babies, and using the NBAS, found significant differences between groups:89

Ann Murray et al. compared 15 unmedicated with 40 epidural-exposed babies and found that the epidural babies still had a depressed NBAS score at five days, with particular difficulty controlling their state. Twenty babies whose mothers had received oxytocin as well as an epidural had even more depression of NBAS scores, which may be explained by their higher rates of jaundice. At one month, epidural mothers found their babies “less adaptable, more intense and more bothersome in their behavior.” These differences could not be explained by the more difficult deliveries and subsequent maternal-infant separations associated with epidurals.90

Carol Sepkoski et al. compared 20 epidural babies with 20 unmedicated babies, and found less alertness and ability to orient for the first month of life. The epidural mothers spent less time with their babies in the hospital, in direct proportion to the total dose of bupivacaine administered.91 Deborah Rosenblatt et al. tested epidural babies with NBAS over six weeks and found maximal depression on the first day. Although there was some recovery, at three days epidural babies still cried more easily and more often; aspects of this problem (“control of state”) persisted for the full six weeks.92

Although these older studies used conventional epidurals, the total dose of bupivacaine administered to the mothers (in these studies, mean doses of 61.6 mg,93 112.7 mg,94 and 119.8 mg,95 respectively) was largely comparable to more recent low-dose studies (for example, 67.5 mg,96 91.1 mg,97 and 101.1 mg98).

These neurobehavioral studies highlight the possible impact of epidurals on newborns and on the evolving mother-infant relationship. In their conclusions, the researchers express concern about “the importance of first encounters with a disorganized baby in shaping maternal expectations and interactive styles.”99

Animal Studies
Animal studies suggest that the disruption of maternal hormones caused by epidurals, described above, may also contribute to maternal-infant difficulties. Researchers who administered epidurals to laboring sheep found that the epidural ewes had difficulty bonding to their newborn lambs, especially those in first lambing with an epidural administered early in labor.100

There are no long-term studies of the effects of epidural analgesia on exposed human offspring. However, studies on some of our closest animal relatives give cause for concern. M. S. Golub et al. administered epidural bupivacaine to pregnant rhesus monkeys at term and followed the development of the exposed offspring to age 12 months (equivalent to four years in human offspring). She found that milestone achievement was abnormal in these monkeys: at six to eight weeks they were slow in starting to manipulate, and at ten months the increase in “motor disturbance behaviors” that normally occurs was prolonged.101 The author concludes, “These effects could occur as a result of effects on vulnerable brain processes during a sensitive period, interference with programming of brain development by endogenous [external] agents or alteration in early experiences.”102

Breastfeeding
As with neurobehavior, effects on breastfeeding are poorly studied, and more recent randomized controlled trials comparing exposure to epidural and opiate drugs are especially misleading because opiates have a well-recognized negative effect on early breastfeeding behavior and success.103-107

Epidurals may affect the experience and success of breastfeeding through several mechanisms. First, the epidural-exposed baby may have neurobehavioral abnormalities caused by drug exposure that are likely to be maximal in the hours following birth”ha critical time for the initiation of breastfeeding. Recent research has found (rather obviously) that the higher the newborn’s neurobehavior score, the higher his or her score for breastfeeding behavior.108

In another study, the baby’s breastfeeding abilities, as measured by the Infant Breastfeeding Assessment Tool (IBFAT), were highest among unmedicated babies, lower for babies exposed to epidurals or IV opiates, and lowest for babies exposed to both. Infants with lower scores were weaned earlier, although overall, similar numbers in all groups were breastfeeding at six weeks.109 In other research, babies exposed to epidurals and spinals were more likely to lose weight in the hospital, which may reflect poor feeding efficiency.110 Other research has suggested that newborn breastfeeding behavior and NACS scores may be normal when an ultra-low-dose epidural is used, although even in this study, babies with higher drug levels had lower neurobehavior (NACS) scores at “Ntwo hours.111

Second, epidurals may affect the new mother, making breastfeeding more difficult. This situation is likely if she has experienced a long labor, an instrumental delivery, or separation from her baby, all of which are more likely following an epidural. Hormonal disruptions may also contribute, as oxytocin is a major hormone of breastfeeding.

One study found that babies born after epidurals were less likely to be fully breastfed on hospital discharge; this was a special risk for epidural mothers whose babies did not feed in the first hour after birth.112 A Finnish survey records that 67 percent of women who had labored with an epidural reported partial or full formula feeding in the first 12 weeks compared to 29 percent of nonepidural mothers; epidural mothers were also more likely to report having “not enough milk.”113

Two groups of Swedish researchers have looked at the subtle but complex breastfeeding and prebreastfeeding behavior of unmedicated newborns. One group has documented that when placed skin-to-skin on the mother’s chest, a newborn can crawl up, find the nipple, and self-attach.114 Newborns affected by opiate drugs in labor or separated from their mothers briefly after birth lose much of this ability. The other Swedish group found that newborns exposed to labor analgesia (mostly opiates, but including some epidurals) were also disorganized in their prefeeding behavior”hnipple massage and licking, and hand sucking”hcompared to unmedicated newborns.115

Satisfaction with Birth
Obstetric care providers have assumed that control of pain is the foremost concern of laboring women and that effective pain relief will ensure a positive birth experience. In fact, there is evidence that the opposite may be true. Several studies have shown that women who use no labor medication are the most satisfied with their birth experience at the time,116 at six weeks,117 and at one year after the birth.118 In a UK survey of 1,000 women, those who had used epidurals reported the highest levels of pain relief but the lowest levels of satisfaction with the birth, probably because of the higher rates of intervention.

Finally, it is noteworthy that caregiver preferences may to a large extent dictate the use of epidurals and other medical procedures for laboring women. One study found that women under the care of family physicians with a low mean use of epidurals were less likely to receive monitoring and Pitocin, to deliver by cesarean, and to have their babies admitted to newborn special care.119

 

Conclusion
Epidurals have possible benefits but also significant risks for the laboring mother and her baby. These risks are well documented in the medical literature but may not be disclosed to the laboring woman. Women who wish to avoid the use of epidurals are advised to choose caregivers and models of care that promote, support, and understand the principles and practice of natural and undisturbed birth.

 

 

Sarah J. Buckley is a family physician, an internationally published writer, and a full-time mother to Emma, Zoe, Jacob, and Maia Rose, all born at home. She is the author of Gentle Birth, Gentle Mothering: The wisdom and science of gentle choices in pregnancy, birth, and parenting, published in early 2006. To read more from Sarah J. Buckley, and to order her book, visit www.sarahjbuckley.com.

 

 

Originally published in Mothering magazine Issue 133

NOTES
1. G. R. Hamilton and T. F. Baskett, “In the Arms of Morpheus: The Development of Morphine for Postoperative Pain Relief” Can J Anaesth 47, no. 4 (2000): 367-374.
2. E. Declercq et al., Listening to Mothers: Report of the First National U.S. Survey of Women’s Childbearing Experiences (New York: Maternity Center Association, October 2002): 1.
3. Canadian Institute for Health Information, Giving Birth in Canada: A Regional Profile (Ontario: CIHA, 2004):7
4. National Health Service, NHS Maternity Statistics, England: 2003-04 (Crown Copyright, 2005): 6.
5. E. D. Hodnett, “Pain and Women’s Satisfaction with the Experience of Childbirth: A Systematic Review” Am J Obstet Gynecol 186, Supplement 5 (2002): S160-S172.
6. S. J. Buckley, “Ecstatic Birth: The Hormonal Blueprint of Labor” Mothering no. 111 (March-April 2002): http://mothering.com/pregnancy-birth/ecstatic-birth-the-hormonal-blueprint-of-labor
7. World Health Organization, Care in Normal Birth: A Practical Guide. Report of a Technical Working Group (Geneva: World Health Organization, 1996): 16.
8. V. A. Rahm et al., “Plasma Oxytocin Levels in Women During Labor With or Without Epidural Analgesia: A Prospective Study” Acta Obstet Gynecol Scand 81, no. 11 (November 2002): 1033-1039.
9. R. M. Stocche et al., “Effects of Intrathecal Sufentanil on Plasma Oxytocin and Cortisol Concentrations in Women During the First Stage of Labor” Reg Anesth Pain Med 26, no. 6 (November-December 2001): 545-550.
10. Ibid.
11. C. F. Goodfellow et al., “Oxytocin Deficiency at Delivery with Epidural Analgesia” Br J Obstet Gynaecol 90, no. 3 (March 1983): 214-219.
12. O. Behrens et al., “Effects of Lumbar Epidural Analgesia on Prostaglandin F2 Alpha Release and Oxytocin Secretion During Labor” Prostaglandins 45, no. 3 (March 1993): 285-296.
13. M. Brinsmead et al, “Peripartum Concentrations of Beta Endorphin and Cortisol and Maternal Mood States” Aust NZ J Obstet Gynaecol 25, no. 3 (August 1985): 194-197.
14. G. Bacigalupo et al., “Quantitative Relationships between Pain Intensities during Labor and Beta-endorphin and Cortisol Concentrations in Plasma. Decline of the Hormone Concentrations in the Early Postpartum Period.” J Perinat Med 18, no. 4 (1990): 289-296.
15. A. Costa et al., “Adrenocorticotropic Hormone and Catecholamines in Maternal, Umbilical and Neonatal Plasma in Relation to Vaginal Delivery” J Endocrinol Invest 11, no. 10 (November 1988): 703-709.
16. M. Odent, “The Fetus Ejection Reflex” in The Nature of Birth and Breastfeeding (Sydney: Ace Graphics, 1992): 29-43.
17. R. P. Lederman et al., “Anxiety and Epinephrine in Multiparous Women in Labor: Relationship to Duration of Labor and Fetal Heart Rate Pattern” Am J Obstet Gynecol 153, no. 8 (15 December 1985): 870-877.
18. G. Arici et al., “The Effects of Bupivacaine, Ropivacaine and Mepivacaine on the Contractility of Rat Myometrium” Int J Obstet Anesth 13, no. 2 (April 2004): 95-98.
19. B. L. Leighton and S. H. Halpern, “The Effects of Epidural Analgesia on Labor, Maternal, and Neonatal Outcomes: A Systematic Review” Am J Obstet Gynecol 186, Supplement 5 (May 2002): S69-S77.
20. Ibid.
21. E. Lieberman et al., “Changes in Fetal Position During Labor and their Association with Epidural Analgesia” Obstet Gynecol 105, no. 5, Part I (May 2005): 974-982.
22. S. E. Ponkey et al., “Persistent Fetal Occiput Posterior Position: Obstetric Outcomes” Obstet Gynecol 101, no. 5, pt. 1 (May 2003): 915-920.
23. COMET Study Group UK, “Effect of Low-Dose Mobile versus Traditional Epidural Techniques on Mode of Delivery: A Randomised Controlled Trial” The Lancet 358, no. 9275 (7 July 2001): 19-23.
24. J. H. Johnson et al., “Immediate Maternal and Neonatal Effects of Forceps and Vacuum-Assisted Deliveries” Obstet Gynecol 103, no. 3 (March 2004): 513-518.
25. B. S. Jhawar et al., “Risk Factors for Intracranial Hemorrhage Among Full-Term Infants: A Case-Control Study” Neurosurgery 52, no. 3 (March 2003): 581-590 (discussion, 588-590).
26. W. G. McBride et al., “Method of Delivery and Developmental Outcome at Five Years of Age” Med J Aust 1, no. 8 (21 April 1979): 301-304.
27. B. D. Wesley et al., “The Effect of Forceps Delivery on Cognitive Development” Am J Obstet Gynecol 169, no. 5 (November 1993): 1091-1095.
28. S. H. Poggi et al., “Effect of Epidural Anaesthesia on Clinician-Applied Force During Vaginal Delivery” Am J Obstet Gynecol 191, no. 3 (September 2004): 903-906.
29. See Note 19.
30. C. L. Roberts et al., “Rates for Obstetric Intervention Among Private and Public Patients in Australia: Population Based Descriptive Study” Br Med J 321, no. 7254 (15 July 2000): 137-141.
31. See Note 19.
32. E. Lieberman and C. O’Donoghue, “Unintended Effects of Epidural Analgesia During Labor: A Systematic Review” Am J Obstet Gynecol 186, Supplement 5 (May 2002): S31-S68.
33. J. A. Thorp et al., “The Effect of Continuous Epidural Analgesia on Cesarean Section for Dystocia in Nulliparous Women” vAm J Obstet Gynecol 161, no. 3 (September 1989): 670-675.
34. See Note 23.
35. L. M. Goetzl, “Obstetric Analgesia and Anesthesia” ACOG Practice Bulletin, Clinical Management Guidelines for Obstetrician-Gynecologists no. 36, Obstet Gynecol 100, no. 1 (July 2002): 177-191.
36. L. J. Mayberry et al., “Epidural Analgesia Side Effects, Co-Interventions, and Care of Women During Childbirth: A Systematic Review” Am J Obstet Gynecol 186, Supplement 5 (2002): S81-S93.{C}
37. D. B. Scott and B. M. Hibbard, “Serious Non-Fatal Complications Associated with Extradural Block in Obstetric Practice” Br J Anaesthv 64, no. 5 (May 1990): 537-541.
38. See Note 36.
39. See Note 35.
40. See Note 36.
41. D. Buggy and J. Gardiner, “The Space Blanket and Shivering During Extradural Analgesia in Labour” vActa Anaesthesiol Scand 39, no. 4 (May 1995): 551-553.
42. See Note 36.
43. Ibid.
44. See Note 19.
45. See Note 32.
46. E. Lieberman et al., “Epidural Analgesia, Intrapartum Fever, and Neonatal Sepsis Evaluation” Pediatrics 99, no. 3 (March 1997): 415-419.
47. P. DeBalli and T. W. Breen, “Intrathecal Opioids for Combined Spinal-Epidural Analgesia During Labour” CNS Drugs 17, no. 12 (2003): 889-904 (892-893).
48. N. S. Saunders et al., “Neonatal and Maternal Morbidity in Relation to the Length of the Second Stage of Labour” Br J Obstet Gynaecol 99, no. 5 (May 1992): 381-385.
49. L. St. George and A. J. Crandon, “Immediate Postpartum Complications” Aust NZ J Obstet Gynaecol 30, no. 1 (February 1990): 52-56.
50. E. F. Magann et al., “Postpartum Hemorrhage after Vaginal Birth: An Analysis of Risk Factors” South Med J 98, no. 4 (April 2005): 419-422.
51. T. M. Eggebo and L. K. Gjessing, ["Hemorrhage After Vaginal Delivery"], Tidsskr Nor Laegeforen 120, no. 24 (10 October 2000): 2860-2863.
52. B. Ploeckinger et al., “Epidural Anaesthesia in Labour: Influence on Surgical Delivery Rates, Intrapartum Fever and Blood Loss” Gynecol Obstet Invest 39, no. 1 (1995): 24-27.
53. L. Gilbert et al., “Postpartum Haemorrhage: A Continuing Problem” Br J Obstet Gynaecol 94, no. 1 (January 1987): 67-71.
54. See Note 48.
55. See Note 35.
56.M. J. Paech et al., “Complications of Obstetric Epidural Analgesia and Anaesthesia: A Prospective Analysis of 10,995 Cases” Int J Obstet Anesth 7, no. 1 (January 1998): 5-11.
57. P. C. Stride and G. M. Cooper, “Dural Taps Revisited: A 20-Year Survey from Birmingham Maternity Hospital” Anaesthesia 48, no. 3 (March 1993): 247-255.
58. S. N. Costigan and J. S. Sprigge, “Dural Puncture: The Patients’ Perspective. A Patient Survey of Cases at a DGH Maternity Unit 1983-1993″ Acta Anaesthesiol Scand 40, no. 6 (July 1996): 710-714.
59.. See Note 56.
60. See Note 37.
61. See Note 56.
62. D. B. Scott and M. E. Tunstall, “Serious Complications Associated with Epidural/Spinal Blockade in Obstetrics: A Two-Year Prospective Study” Int J Obstet Anesth 4, no. 3 (July 1995): 133-139.
63. J. S. Crawford, “Some Maternal Complications of Epidural Analgesia for Labour” Anaesthesia 40, no. 12 (December 1985): 1219-1225.
64. F. Reynolds, “Epidural Analgesia in Obstetrics” Br Med J 299, no. 6702 (September 1989): 751-752.
65. See Note 37.
66. See Note 62.
67. See Note 63.
68. See Note 64.
69. MIDIRS and the NHS Centre for Reviews and Dissemination, “Epidural Pain Relief During Labour” in Informed Choice for Professionals (Bristol: MIDIRS, 1999): 5.
70. See Note 37.
71. R. Fernando et al., “Neonatal Welfare and Placental Transfer of Fentanyl and Bupivacaine During Ambulatory Combined Spinal Epidural Analgesia for Labour” Anaesthesia 52, no. 6 (June 1997): 517-524.
72. J. Littleford, “Effects on the Fetus and Newborn of Maternal Analgesia and Anesthesia: A Review” Can J Anaesth51, no. 6 (June-July 2004): 586-609.
73. G. Capogna, “Effect of Epidural Analgesia on the Fetal Heart Rate” Eur J Obstet Gynecol Reprod Biol 98, no. 2 (October 2001): 160-164.
74. C. J. Aldrich et al., “The Effect of Maternal Posture on Fetal Cerebral Oxygenation During Labour” Br J Obstet Gynaecol 102, no. 1 (January 1995): 14-19.
75. E. Lieberman et al., “Intrapartum Maternal Fever and Neonatal Outcome” Pediatrics 105, no. 1, pt. 1 (January 2000): 8-13.
76. L. Impey et al., “Fever in Labour and Neonatal Encephalopathy: A Prospective Cohort Study” Br J Obstet Gynaecol 108, no. 6 (June 2001): 594-597.
77. See Note 32.
78. Ibid.
79. K. Thorngren-Jerneck and A. Herbst, “Low 5-Minute Apgar Score: A Population-Based Register Study of 1 Million Term Births” Obstet Gynecol 98, no. 1 (2001): 65-70.
80. M. Kumar and B. Paes, “Epidural Opioid Analgesia and Neonatal Respiratory Depression” J Perinatol 23, no. 5 (July-August 2003): 425-427.
81. Ibid.
82. T. Hale, Medications and Mothers’ Milk (Amarillo, TX: Pharmasoft, 1997): 76.
83. See Note 71.
84. T. Hale, “The Effects on Breastfeeding Women of Anaesthetic Medications Used During Labour” The Passage to Motherhood Conference, Brisbane, Australia (1998).
85. See Note 32.
86. W. Camann and T. B. Brazelton, “Use and Abuse of Neonatal Neurobehavioral Testing” Anesthesiology 92, no. 1 (January 2000): 3-5.
87. R. Gaiser, “Neonatal Effects of Labor Analgesia” Int Anesthesiol Clin 40, no. 4 (Fall 2002): 49-65.
88. S. H. Halpern et al., “The Neurologic and Adaptive Capacity Score Is Not a Reliable Method of Newborn Evaluation” Anesthesiology 94, no. 6 (June 2001): 958-962.
89. See Note 32.
90. A. D. Murray et al., “Effects of Epidural Anesthesia on Newborns and their Mothers” Child Dev 52, no. 1 (March 1981): 71-82.
91. C. M. Sepkoski et al., “The Effects of Maternal Epidural Anesthesia on Neonatal Behavior During the First Month” Dev Med Child Neurol 34, no. 12 (December 1992): 1072-1080.
92. D. B. Rosenblatt et al., “The Influence of Maternal Analgesia on Neonatal Behaviour: II. Epidural Bupivacaine” Br J Obstet Gynaecol 88, no. 4 (April 1981): 407-413.
93. See Note 90.
94. See Note 91.
95. See Note 92.
96. See Note 71.
97. J. R. Loftus et al., “Placental Transfer and Neonatal Effects of Epidural Sufentanil and Fentanyl Administered with Bupivacaine During Labor” Anesthesiology 83, no. 3 (1995): 300-308.
98. See Note 23.
99. See Note 90: 71.
100. D. Krehbiel et al., “Peridural Anesthesia Disturbs Maternal Behavior in Primiparous and Multiparous Parturient Ewes” Physiol Behav 40, no. 4 (1987): 463-472.
101. M. S. Golub and S. L. Germann, “Perinatal Bupivacaine and Infant Behavior in Rhesus Monkeys” Neurotoxicol Teratol 20, no. 1 (January-February 1998): 29-41.
102. M. S. Golub, “Labor Analgesia and Infant Brain Development” Pharmacol Biochem Behav 55, no. 4 (1996): 619-628 (619).
103. L. Righard and M. O. Alade, “Effect of Delivery Room Routines on Success of First Breast-Feed” The Lancet 336, no. 8723 (November 1990): 1105-1107.
104. M. K. Matthews, “The Relationship Between Maternal Labour Analgesia and Delay in the Initiation of Breastfeeding in Healthy Neonates in the Early Neonatal Period” Midwifery 5, no. 1 (March 1989): 3-10.
105. A. B. Ransjo-Arvidson et al., “Maternal Analgesia During Labor Disturbs Newborn Behavior: Effects on Breastfeeding, Temperature, and Crying” Birth 28, no. 1 (March 2001): 5-12.
106. E. Nissen et al., “Effects of Maternal Pethidine on Infants Developing Breast Feeding Behaviour” Acta Paediatr 84, no. 2 (February 1995): 140-145.
107. L. Rajan, “The Impact of Obstetric Procedures and Analgesia/Anaesthesia During Labour and Delivery on Breast Feeding” Midwifery 10, no. 2 (June 1994): 87-103.
108. S. Radzyminski, “Neurobehavioral Functioning and Breastfeeding Behavior in the Newborn” J Obstet Gynecol Neonatal Nurs 34, no. 3 (May-June 2005): 335-341.
109. J. Riordan et al., “The Effect of Labor Pain Relief Medication on Neonatal Suckling and Breastfeeding Duration” J Hum Lact 16, no. 1 (February 2000): 7-12.
110. K. G. Dewey et al., “Risk Factors for Suboptimal Infant Breastfeeding Behavior, Delayed Onset of Lactation, and Excess Neonatal Weight Loss” Pediatrics 112, no. 3, pt. 1 (September 2003): 607-619.
111. S. Radzyminski, “The Effect of Ultra Low Dose Epidural Analgesia on Newborn Breastfeeding Behaviors” J Obstet Gynecol Neonatal Nurs 32, no. 3 (May-June 2003): 322-331.
112. D. J. Baumgarder et al., “Effect of Labor Epidural Anesthesia on Breast-Feeding of Healthy Full-Term Newborns Delivered Vaginally” J Am Board Fam Pract 16, no. 1 (January-February 2003): 7-13.
113. P. Volmanen et al., “Breast-Feeding Problems After Epidural Analgesia for Labour: A Retrospective Cohort Study of Pain, Obstetrical Procedures and Breast-Feeding Practices” Int J Obstet Anesth 13, no. 1 (2004): 25-29.
114. See Note 103.
115. See Note 105.
116. S. Kannan et al., “Maternal Satisfaction and Pain Control in Women Electing Natural Childbirth” Reg Anesth Pain Medvv 26, no. 5 (September-October 2001): 468-472.
117. J. M. Green et al., “Expectations, Experiences, and Psychological Outcomes of Childbirth: A Prospective Study of 825 Women” Birth 17, no. 1 (March 1990): 15-24.
118. B. M. Morgan et al., “Analgesia and Satisfaction in Childbirth (The Queen Charlotte’s 1000 Mother Survey)” The Lancet 2, no. 8302 (9 October 1982): 808-810.
119. M. C. Klein et al., “Epidural Analgesia Use as a Marker for Physician Approach to Birth: Implications for Maternal and Newborn Outcomes” Birth 28, no. 4 (December 2001): 243-248.