Medications to Provide Pain Relief and Assist Labor

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Medications to Provide Pain Relief and Assist Labor

Women learn many techniques in prenatal classes that help them cope with discomforts of childbirth, such as contraction-relaxation control and breathing exercises. You have several other options for pain relief if these exercises don't help you cope with the pain of your labor.

Approximately two-thirds of all women in the United States receive pain-relieving medications during labor. The size of your hospital (a small community vs. a large academic or teaching hospital) can affect the choices available for pain relief, but most hospitals can accommodate your needs. An anesthesiologist — a doctor who is an expert in pain relief — may work with your doctor to pick the best method for you.

Medications are also available to speed up or "augment" your labor, or induce or start up your labor. The following are commonly used techniques and medications to relieve pain or assist your labor during childbirth: anesthetics, analgesics and oxytocics.

Anesthetics

These medications are given by injection during labor to numb you, but not put you to sleep. Anesthetics can be given by one of several commonly used techniques:

Paracervical anesthesia. In this technique, local anesthesia medication is injected into the tissues around the cervix to numb the pain caused by cervical dilation. The effect lasts an hour or two, and additional injections can be given if necessary. Paracervical anesthesia is usually given during the last part of labor but before your cervix is fully dilated. Anesthetics given by paracervical block can slow the baby's heartbeat and should be avoided if your obstetrician has concerns about your baby's heartbeat pattern during labor.

Pudendal block. This form requires two injections, one on each side inside the vagina, to numb the nerves of the vaginal area and perineum (the region between the vagina and rectum). This is most commonly used during the second stage of labor, when you are fully dilated and pushing out the baby's head. The numbness provided is usually quick-acting, effective and considered safe for you and your baby. This technique can be used for vaginal deliveries, repairing episiotomy tears/lacerations of the perineum, and can be used by your doctor to relieve pain associated with a vacuum extractor or outlet forceps-assisted vaginal delivery of your baby's head. Risks of pudendal blocks include patchy, incomplete numbness, or accidental injection of the medication into the blood vessels around the cervix and vagina, which could have a toxic effect on your breathing, heart rate, blood pressure and brain function, causing seizures or convulsions.

Caudal block. Caudal block is also called saddle-block anesthesia because it numbs the lower genital and perineal area that would come into contact with the saddle of a horse. It is injected into the spinal column of your lower back and mixes with your spinal fluid. It works rapidly, but has powerful side effects that include unusually low blood pressure, occasional post-delivery headache, temporary sluggish or loss of bladder function, and in rare cases, convulsions or infection.

Epidural anesthesia. Epidural anesthesia is injected through a catheter in the epidural space, the space between the dura mater (the sheath surrounding the spinal cord) and the bony vertebrae of your spine, numbing your body from the waist down. The medication takes about 3 to 5 minutes to work and provides complete relief in about 85 percent of women, partial relief in 12 percent and no relief in 3 percent. It can also be used for Caesarean section, but the strength and amount of medication used are greater than those used for labor and vaginal birth. Before receiving an epidural, you'll need intravenous fluids to prevent your blood pressure from dropping — the most common side effect of this form of anesthesia. The epidural catheter remains in your back during labor so medication can be given to keep you pain-free. It can remain in place for a short time after vaginal or Caesarean delivery for postpartum pain relief.

A standard epidural uses intermittent boluses or repeated doses of medication given every 1 to 2 hours as needed during labor and delivery. Medication can also be delivered continuously in lower doses, known as a continuous low-dose epidural, which has several advantages over a standard epidural. A small amount of medication continuously flows through the epidural catheter at a rate controlled by an infusion pump so that pain relief will be less likely to wear off during your delivery. Continuous epidural numbs your sensation but doesn't affect the motor power of your legs, unlike a standard epidural. The continuous low-dose epidural also decreases the likelihood of side effects but will not eliminate them completely. Another form of epidural is patient-controlled epidural anesthesia (PCEA), which allows you to control your own pain relief with a push-button device that releases controlled amounts of drug through the epidural catheter when you need it. The PCEA device only releases a certain amount of medication over time so you won't overmedicate yourself. Some studies have shown that PCEAs use less medication than standard and continuous epidurals, are less likely to lower blood pressure, yet provide more effective pain relief.

Potential side effects of all epidurals include mild to severe postpartum headache, difficulty urinating or walking after delivery, or abnormally elevated body temperature. Because the epidural provides numbness and pain relief from your waist down, it can prolong your labor or diminish your ability to push out your baby, leading to use of a vacuum or forceps, or possibly a Caesarean section to help deliver your baby. Epidural medications can temporarily slow the baby's heartbeat because these drugs can lower blood pressure.

Analgesics

Analgesics are used for pain relief, without total loss of physical sensation or feeling. Although they won't always stop pain completely, analgesics do lessen it. Narcotic analgesics such as demerol are most frequently used to relieve the pain of labor. They are usually given by injection into a muscle or vein and generally do not prolong or delay contractions of well-established labor. Narcotics may produce such side effects as nausea, vomiting, a slow breathing rate and decreased blood pressure. The baby's ability to breath may also be slower than normal at birth, but this effect generally is short-term and can be reversed with anti-narcotic medication such as naloxone.

Oxytocics

These medications are used to start (induce) or speed up labor. The most commonly used is an intravenous medication called oxytocin (Pitocin), which is pumped slowly into the vein by an infusion pump. It's a synthetic version of a hormone that helps to start contractions and also helps to release your breast milk during breast-feeding. Some women report that medications used to induce labor cause stronger contractions than those that occur naturally; these contractions can be more frequent than natural ones, depending on the speed of the oxytocin infusion and the strength of the dose. Occasionally, oxytocics cause such frequent, strong contractions that oxygen to the baby is reduced, leading to fetal distress. Expectant mothers who have labor induced, especially first-time mothers, tend to have Caesarean delivery more often than mothers whose labor starts naturally.

Among the reasons for inducing labor are prolonged pregnancy, also called post-term or post-dates pregnancy; pregnancy-induced or chronic hypertension; diabetes mellitus; previous stillbirth; intrauterine growth restriction; and premature rupture of membranes. Reasons not to induce labor include placenta previa (a placenta covering the cervical opening), abruptio placenta (a placenta that separates prematurely from the uterus before the baby delivers) and unusual presentation of the baby, such as breech position, that would make vaginal delivery hazardous or impossible. Induction of labor is not usually done if your baby is suspected of being too big to fit through your pelvis (cephalopelvic disproportion) or if you have an excessive amount of amniotic fluid (polyhydramnios), a genital herpes infection, a multiple birth (twins or more), or a worrisome fetal heart rate pattern or signs of fetal distress.

Last updated:	September 29, 2004
Reviewed By:	Faculty of Harvard Medical School