Categories: Pain Relief Drugs and Pharmaceuticals Labor and Birth

As an expectant mother approaching your due date, a concern that looms large in your mind is the pain that you will experience during labor. Will you be able to cope?

An original article for the website by Nancy H. Sullivan, CNM, MS, FACNM; Oregon Health Sciences University School of Nursing.

Is it important to you to experience your labor without drugs, or have you already decided that drugs are the only way to go? Expectations regarding labor pain are colored by past experience, including your own and that of your friends and family. However, the intensity of labor pain, the length of time labor lasts, and women's individual response to the pain vary widely. Also, the environment in which you give birth and the support you receive from your caregivers and companions will affect your reaction to pain and your ability to cope (1). Unfortunately, there is no way to answer the questions, "How painful will my labor be, and will I be able to handle it?" until the day of your labor arrives. In the meantime, you need to find out as much as you can about labor pain, what causes it, and what help you have available to cope with it when the time does come.

The ideal time for you to discuss labor pain and seek information about the various options available to assist in pain relief with your midwife or doctor is during your pregnancy, well before labor begins. There are a great many choices for pain relief, both pharmacological (drugs) and non-pharmacological (without drugs). Your caregiver should let you know what is available in the setting in which you plan to give birth (not all options are available in all settings), explain to you the relative risks and benefits of various methods, help you make a plan that makes you comfortable, and support you in your decision. This is not to say that any decision made several months before labor starts is written in stone; a key attribute on both your part and that of your caregiver and supporters should be flexibility, since the character of your labor is an unknown factor. A fast, relatively easy labor may require little other than support and encouragement, while a long, difficult labor will likely use many of the available options.

The ideal pain relief in labor should provide good analgesia, be safe for the mother and baby, be predictable and constant in its effects, be reversible if necessary, be easy to administer, be under the control of the mother; and should not interfere with uterine contractions, or interfere with mobility (2). Good pain relief in labor is not the same as a perception of personal control or satisfaction in childbirth. In other words, you may have significant pain during your labor, but feel in control during the process and have great satisfaction afterward. On the other hand, you might have total pain relief during your labor, but feel totally out of control and unhappy about your experience when it is over.

In most languages, the word for the process of giving birth describes a process of work (labor), not of pain. Remember that labor pain is more than a physiological process; coping with labor pain is emotional and complex and results in feelings of fulfillment and achievement for women. Therefore, satisfaction with labor is not necessarily related to the efficacy of pain relief. Your midwife should work with you during the prenatal period to identify personal coping strategies and encourage you to make efficient and effective use of these resources (2).

Consider this recent letter to the editor of the New York Times, published on the Op-Ed page:

The distinction between pain relief and satisfaction in childbirth is sometimes lost on obstetric providers who advocate for epidural anesthesia for all laboring women. Interestingly, this same distinction was lost on James Simpson, the surgeon who introduced the use of chloroform in 1847. In an article comparing the use of chloroform to the use of epidurals in obstetrics, a recent author (3) states, "That labour pain is fundamentally different from the pain of surgery may not have occurred and certainly was of not matter to Simpson. His background as a surgeon served to convince him of the pathological nature of all pain and thus, he was prevented from recognizing the positive or productive characteristics of labour pain."{mospagebreak}

What are factors that predict the level of labor pain? According to one study, young maternal age, first baby, use of oxytocin to induce or augment the labor, and a history of dysmenorrhea (menstrual cramps) are associated with increased labor pain, while regular aerobic exercise performed during pregnancy and attendance at childbirth education classes are associated with decreased pain in labor. In a study of factors associated with fear of delivery during second pregnancies, the two most important causes were first deliveries that ended with cesareans or vacuum extractions. Mothers with fear of second delivery had received epidural anesthesia more often than controls; other pain relief methods were used similarly (4).

A 1998 study, involving 4,171 women, of the methods used by nurse-midwives in the U.S. to manage pain in labor showed that the majority (84%) use non-drug methods, while about half (49%) also use drugs. The breakdown of methods used is shown in the two tables below.

Non-pharmacologic pain relief measures in labor by Nurse-Midwives in U.S. (N=4,171)

Non-pharmacologic method	Percentage using
Paced breathing	55.2%
Activity/Position change	42.4%
Massage/Therapeutic touch	17.3%
Visualization/Relaxation	17.0%
Hydrotherapy (bath, shower, jacuzzi)	14.9%
Local application of heat or cold	2.2%
Music/ Audio analgesia	0.8%
Other methods	0.4%
Any methods used	84.8%
No methods used	15.2%

(The CNM Data Group, 1998. J Nurse-Midwifery 43:77-82)

Pharmacologic Pain Relief in Labor by Nurse-Midwives in U.S.(N=4,171)

Pharmacologic Method	Percentage using
Narcotic analgesia	30.0
Epidural analgesia	18.7
Tranquilizers and Sedatives	6.5
Intrathecal narcotics	5.3
Any pharmacologic methods	49.0
None	51.0

(The CNM Data Group, 1998. J Nurse-Midwifery 43:77-82)

In a recent study of methods of pain control used during labor in the U.K., the authors found that administration of nitrous oxide mixed with oxygen and administered by face mask is the most popular method (formerly popular in the U.S., this method is now virtually unavailable); non-drug methods are second (lumped together in this study), and pethidine (Demerol in the U.S.) is third, with epidural anesthesia used for only 18%. The trends for labor pain relief in the U.K. are shown in the table below. As you can see, methods in vogue during one period of time fall from favor in another period, usually as serious side effects are made known or safer methods are developed.

LABOR PAIN RELIEF, United Kingdom, 1946-1990 (%)

	1946	1958	1970	1984	1990
Chloroform	17	0	0	0	0
Nitrous Oxide/Air	16	56	2	0	0
Nitrous Oxide/Oxygen	0	0	52	54	60
Trilene	0	25	7	0	0
Pethidine (meperidine, Demerol)	0	56	69	36	37
Epidural or spinal	0	3	9	17	18
Non-drug	0	1	2	13	58
None	68	34	2	2	NR

Findley I, Chamberlain G. Relief of pain: clinical review. BMJ 1999;318:927-930.{mospagebreak}

PSYCHOSOCIAL SUPPORT IN LABOR
The presence of a professional support person (doula) in labor has been shown to be a significant help to laboring women in managing their pain. In addition, a doula's presence will shorten labor by an average of 2.8 hours, result in a decreased use of oxytocin, result in a decrease in operative and instrumental deliveries, and decrease requests for epidural anesthesia (1). To find out more about doulas, go to the doula page.

POSITION CHANGES DURING LABOR
The ability of the mother to change her position during labor, that is, to walk around, sit in a rocking chair or on a birthing ball or birth stool, squat on her haunches, get on her hands and knees, or assume whatever position feels most comfortable to her, has been shown to shorten the length of labor, decrease the use of oxytocin to augment labor, and decrease the use of epidural and opioid pain medications in labor (1).

OTHER NON-DRUG PAIN RELIEF METHODS
Other non-drug pain relief methods that may be useful, in early labor for almost all women, and throughout labor for some, include the following (1): hypnosis (prior to labor), psychoprophylaxis or Lamaze, a conscious focus of cortical brain activity (e.g., paced breathing), biofeedback (not shown to be very effective), acupuncture, transcutaneous electric nerve stimulation (TENS), hydrotherapy (bath, shower, Jacuzzi), music and audio analgesia, aromatherapy, and injection of sterile water just under the skin on the lower back, whic can be effective for low back pain. Of these methods, the ones that are the most effective, according to Penny Simkin (5), are immersion in water and position changes or movement.

SEDATIVES AND HYPNOTIC AGENTS USED IN LABOR (6)
Barbiturates are sometimes used in "false," prodromal, or early labor when the mother is exhausted but can't rest or sleep because of contractions. The most commonly used barbiturate is secobarbital or Seconal; it easily crosses the placenta, and lasts a long time in the baby's blood. It is associated, even in small doses, with decreased attention span in the newborn. The usual dose is 100 mg po. It does not reduce pain, and can actually increase the reaction to painful stimuli.

Benzodiazepines are similar to the barbiturates; they used to treat anxiety, seizure disorders, and as a pre-operative medication. They also cross the placenta and last a long time. They also have amnesic properties, especially midazolam (Versed); they are associated with lower Apgar scores ( measure of the baby's well-being in the first minutes of life), and have a potential for abuse related to therapeutic effects of anti-anxiety and sedation.

There are other drugs that act as sedatives and relieve nausea and vomiting. Promethazine (Phenergan), hydroxyzine (Vistaril), and diphenhydramine (Benadryl) are three examples of drugs that are actually antihistamines that may be helpful in "false," prodromal, or early labor. Side effects include dry mouth, urinary retention, and slowing of digestion, as well as low blood pressure, especially while lying down. Phenergan and Vistaril have been associated with some changes in fetal heart rate monitor tracings (decreased beat-to-beat variability) but not with low Apgar scores. Benadryl can cause stimulation instead of drowsiness in certain individuals, but has few adverse side effects and is generally a safe and effective choice. It is frequently used in late pregnancy for women who have sleeping problems.

OPIOIDS (NARCOTICS) USED IN LABOR (6)
In a well-designed study, anesthesiologists from the Karolinska Hospital, Stockholm, demonstrated that opioids given systemically do not actually relieve labor pain. Morphine had been their preferred opioid for labour, until they demonstrated its ineffectiveness. They compared morphine with the more widely used Demerol (Pethidine) and found that neither drug reduced pain scores, while sedation became increasingly severe with successive doses. However, both drugs reduced anxiety and discomfort, and Demerol (Pethidine), but not morphine, produced exhilaration. In other words, opioids, while not eliminating the pain, change the woman's perception of pain and make it more tolerable. All of the opioids have side effects, such as dry mouth, urinary retention (inability to urinate), and decreased gastric motility (sluggish bowels).{mospagebreak}

Morphine is frequently used when the labor is expected to continue for a number of hours. It can be given by injection, in an IV, or in an epidural catheter. It produces drowsiness as well as a perception of decreased pain. These effects lasts a long time; morphine crosses the placenta and causes the baby to sleep too; as seen by a "flattening" of the fetal heart rate monitor tracing.

Meperidine (Demerol or Pethidine), despite studies that show it does not actually decrease labor pain, is still used frequently on many labor units. It can cause respiratory depression (slower and shallower breathing, resulting in less oxygen intake) in both mother and baby; this effect is increased with increasing doses. It frequently causes nausea and vomiting. Demerol, more than other drugs used in labor, has been shown to delay initiation of breastfeeding in first-time moms, especially when given close to the time of birth. It is probably a poor choice for labor, since there are better alternatives available.

Butorphanol (Stadol) and Nalbuphine (Nubain) are synthetic opioids that are popular on some labor units; they appear to be as effective as morphine and Demerol. Unlike Demerol, they are unlikely to cause nausea and vomiting, although they may cause some dizziness and drowsiness. They are also less likely to cause breathing problems in the baby. They are attractive options for women who need something to "take the top off" their labor pain but want to avoid, or are not ready for, an epidural.

Fentanyl (Sublimaze) is another option, especially useful when labor has progressed and become very intense but is not expected to last too much longer. It has greater analgesic potency than morphine or meperidine, a quick onset (5 minutes) when given in an IV, and a short duration (30 to 60 minutes). It can be given several times if needed. It is associated with less nausea and vomiting than morphine or meperidine. Favorable newborn outcomes were reported in a study that compared fentanyl administration with no analgesia in labor.

EPIDURAL ANESTHESIA FOR LABOR AND BIRTH
Epidurals, the most common pharmacological method of labor pain relief, are considered separately in an excellent article by Judith Rooks, CNM, MS, FACNM, on another page of the website. Click here to go to this article.

References:
1. Enkin M, Keirse MJNC et al. (2000). A Guide to Effective Care in Pregnancy and Childbirth, Third Edition. Oxford: Oxford University Press.

2. McCrea H. (1999). Satisfaction in childbirth and perceptions of personal control in pain relief during labor. J Advanced Nurs 29(4):877-884.

3. Mander R. (1998). Analgesia and anaesthesia in childbirth: obscurantism and obfuscation. J Advanced Nursing 28:86-93.

4. Saisto T, Ylikorkala O, Halmesm䫩 E. (1999). Factors associated with fear of delivery in second pregnancies. Obstetrics & Gynecology 94:679-82.

5. Simkin P (1997). Simkin's ratings of comfort measures for childbirth. Waco, TX: Childbirth Graphics.

6. Faucher MA and Brucker MC (2000). Intrapartum Pain: Pharmacologic Management. JOGNN 29:169-80.

 

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The Maternity Center Association's website, MaternityWise, is providing a downloadable (pdf) version of the executive summary of the "Nature and Management of Labor Pain" Symposium papers in the American Journal of Obstetrics & Gynecology. To download it, go to http://www.maternitywise.org/