Overview

You have several pain management options for labor and birth. The availability of specific methods may vary depending on where you give birth and your care provider. Plus, different methods are used during different stages of labor with varying levels of effectiveness. There are separate articles on epidurals and nitrous oxide, the two most popular methods used during labor and birth. This episode covers transcutaneous electric nerve stimulation (TENS), intravenous pain medications, pudendal nerve blocks, local anesthetic injections, and touches on general anesthesia. If you are interested in utilizing any of these methods or have questions about them, please have a more in-depth conversation about the benefits and risks with your doctor or midwife.

Listen Now

Become a Pregnancy Podcast Premium member or log in to access all articles and episodes ad-free.

Article and Resources

Transcutaneous Electrical Nerve Stimulation (TENS)

Transcutaneous electrical nerve stimulation is a non-pharmacological therapy for pain relief. Although you can use a TENS unit for chronic pain, this article focuses on using TENS when you are in labor. Expecting mothers have used TENS as a pain-relieving technique for labor since the 1970s. A TENS machine sends low voltage electrical impulses through the electrodes stuck onto the skin on your lower back to your nerves.

TENS Prevalence and Availability

Availability and use of TENS units vary by country. Outside of the United States, in countries like the U.K. and Canada, TENS are utilized more often. Some hospitals or birth centers may offer the use of a TENS machine. If the venue where you have your baby does not offer TENS, you may be able to purchase and use your unit. These are available to consumers without a prescription at some pharmacies and online. If you are considering purchasing a TENS machine, start with asking your doctor or midwife for recommendations. The cost can range from $30 to several hundred dollars. Units differ in the settings available to control the intensity of the stimulation. Some may have a feature to boost stimulation with the push of a button, which can come in handy during a contraction. Units also differ in the number and size of the pads.

Contraindications for using a TENS Unit

Most expecting mothers are eligible to use a TENS unit. There are a few contraindications for using TENS. Your care provider will not recommend using TENS if you have epilepsy, a pacemaker, or any heart rhythm issues.

How TENS Works

A TENS unit doesn’t numb any sensation, and we do not know exactly why this works. There are a couple of theories on how electrical pulses can help during labor. The first is that they may prevent pain signals from reaching your brain. By this theory, the application of heat, cold, or massage would have a similar effect. The other view of how TENS works is that it stimulates your body to release endorphins, which can mediate the experience of pain.

The stimulation from the TENS machine is a distraction from your contractions. By giving a mother in labor a sense of control, it may alleviate anxiety. TENS may limit the release of catecholamines which have a role in your labor but can also slow it down. Theoretically, if TENS makes you feel more empowered during labor, then your labor may be shorter.

What to Expect with TENS

A TENS unit is a small handheld device with wires coming out of it attached to electrodes in pads that you stick on your skin. Typically, for labor, the pads are placed on your lower back. You can control the intensity of the stimulation and may have the option of a boost button. You will feel a tingling or buzzing sensation where the electrodes are stuck on your back.

It is advised to wait to use a TENS unit until you are in labor. This method seems to be most helpful early on and less effective as contractions get stronger. The unit is not waterproof. If you want to labor in the shower, bathtub, or birth pool, you would need to remove the pads and discontinue use until you are out of the water and dry. You should also avoid placing pads over a scar or broken skin.

TENS Benefits

There are many possible benefits of using TENS during labor in comparison to other pain relief methods. Using TENS does not restrict your mobility. Since it is a handheld device that is battery-operated, you can move around, remain upright, and try different positions. A TENS unit doesn’t require a trained professional like a doctor, midwife, or nurse to operate it. This is something you could use in early labor at home, and you control the intensity of the stimulation and can start or stop at any time. Since you operate the unit, it can give you a sense of control during labor.

TENS Risks

From all of the research I sifted through for this article, no adverse effects are attributed to using a TENS machine. This assumes you are using the device as instructed, like not using it in water, and you don’t fall under the contraindications.

Although there are no risks, there are a few downsides. The electrical stimulation can interfere with electronic fetal monitoring. If you are using electronic monitoring, your doctor or midwife may ask you to discontinue using TENS. Availability of TENS machines may be an issue. Since TENS are not used widely in the United States, it is possible your care provider would not encourage you to use or buy one. You will need someone to put the pads on for you since they go on your back. Since you cannot get the TENS unit or pads wet, if you are getting in a tub or a shower, you would have to remove it, then reapply once dry.

TENS Effectiveness 

A Cochrane Review that includes 17 trials with 1,466 women found there is only limited evidence that TENS reduces labor pain. The majority of women using TENS said they would be willing to use it again in future labor. Researchers reported no adverse effects and noted it does not seem to have any other outcomes for mothers or babies. In another review that looked at all available pain relief methods, they found insufficient evidence on TENS’ effectiveness.

A randomized, double-blind, placebo-controlled trial looked at TENS and tried to find the most effective dose. There were three groups. One used a constant frequency of 100 Hz, another used a varying high frequency of 80-100 Hz, and the third group was a placebo using a unit with no electrical stimulation. They found the group with varying frequencies to be more effective.

To summarize the research, the evidence is not overwhelming that TENS machines make a big difference during labor. The good news is that there is no downside to using one either. If you choose to utilize this device, you will need to experiment with the intensity, frequency, and timing of stimulation that works best for you.

Systemic Analgesics (Intravenous Pain Medications)

Opioids are powerful pain medication drugs. This class of medications includes narcotics like fentanyl, oxycodone, morphine, and heroin. These are considered systemic analgesics and can be given intravenously during labor to help with pain or given in a shot. These drugs have a calming effect and reduce awareness of pain but do not eliminate it.

Typically, intravenous medications are not the method of choice when an epidural is an option. According to ACOG, parenteral opioids have little effect on maternal pain scores, provide unreliable analgesia, and commonly have adverse effects such as nausea and vomiting.

Medications Used in Systemic Analgesics

In the United States, fentanyl, morphine, nalbuphine, butorphanol, and remifentanil are common. These all vary in how quickly they go to work and how long they last. Fentanyl, which is the most common, starts working within 2-4 minutes and lasts 30-60 minutes. Morphine takes effect within 10 minutes with an IV or 30 minutes with an intramuscular injection, then lasts 1-3 hours.

The half-life of these drugs also varies. The half-life is the amount of time it takes for your body to eliminate half of the drug. For fentanyl, the half-life is 3 hours. The half-life of morphine is 2 hours. Some of the other drugs used in the U.S. can take 2-5 hours, or remifentanil is 9-10 minutes. A review of 70 studies did not have sufficient evidence to assess which opioid drug provided the best pain relief with the least adverse effects. For more information on the specifics of the medications used, please talk to your doctor.

Prevalence and Availability of Systemic Analgesics

Hospitals have systemic analgesics available. These are not typically available at a birth center or for a home birth. Unlike an epidural, an anesthesiologist does not need to administer these medications.

How Systemic Analgesics Work

Opioids work by binding to opioid receptors in your brain, spinal cord, and gastrointestinal tract. They trigger dopamine and reduce pain messages to your brain. This class of drugs is also known to be addictive when used over long periods.

Side Effects of Systemic Analgesics

Side effects include nausea, vomiting, and drowsiness. According to ACOG, opioids are associated with adverse effects for the woman and the fetus or newborn, most significantly respiratory depression.

How Systemic Analgesics Affect Your Baby

All opioids cross the placenta. Alterations in the fetal heart rate tracing are common after the administration of opioids. Your doctor will be monitoring your baby’s heart rate to keep an eye on this. These drugs have risks to your baby, including lower Apgar scores, respiratory depression, decreased muscle tone, and difficulty suckling. These side effects in your baby can negatively impact breastfeeding and bonding after birth.

The half-life of opioids in newborns is much longer than in adults. Systemic analgesics are not typically used near the time of delivery and your doctor limits them to the first stage of labor to minimize the effects on your baby.

Pudendal Nerve Block

A pudendal nerve block is an injection of an anesthetic that works to block the pudendal nerve. This nerve goes into two branches, one on each side of your body, and carries sensation from your labia, clitoris, and perineum. This shot is administered transvaginally (through your vagina) in the second stage of labor, just before your baby is born. Your doctor could use a pudendal block to repair a tear or episiotomy, although a local anesthetic is more common for these procedures.

Keep in mind this block will not block any discomfort from contractions. If you are concerned about pain during the second stage in your vagina or perineum, it will help. Even if you have an episiotomy, it is more common to inject a local anesthetic into the tissue before the incision rather than a nerve block.

Medications Used in Pudendal Nerve Blocks

Lidocaine is the most common medication for a pudendal block. There are other options like chloroprocaine or bupivacaine. If this is something you are considering, you can go over the details of the medication options with your care provider because each will have its list of side effects and benefits.

Prevalence and Availability of Pudendal Nerve Blocks

A Pudendal nerve block should be available at any hospital but is an unlikely option at a birth center or home birth.

Contraindications for a Pudendal Nerve Block

The only contraindication to receiving a pudendal nerve block is if you have an allergy to the medications, any infection at the injection site, or a blood clotting disorder.

What to Expect with a Pudendal Nerve Block

For this procedure, you would be on your back, with your legs up. A doctor will insert the needle through your vagina to inject the medication. They may use an ultrasound to assist in guiding the needle. The effects should be almost immediate.

Pudendal Nerve Block Benefits

The benefit of a pudendal nerve block is pain relief in the second stage of labor. It is also possible to use this method with or independent of other pain medications. A double-blind study that paired a pudendal nerve block or a placebo with an epidural found a pudendal nerve block decreased drug use in an epidural and shortened the second stage of labor. The group participants who received the nerve block were more satisfied with their pain relief than the control group who received a placebo.

Pudendal Nerve Block Side Effects and Risks

The most common side effect is discomfort at the injection site. There is a small risk of bleeding or infection. Rare side effects can include damage to the pudendal nerve or damage to organs nearby, like the bladder. There is also the rare possibility of puncturing the pudendal artery, which could be fatal. This is a procedure that is considered safe by a trained medical professional. In the research reviewed for this article, all studies did not find that a pudendal nerve block affected babies.

General Anesthesia

If you are in labor and already have an epidural in place, your doctor or anesthesiologist can adjust the medications to allow for a cesarean. General anesthesia is usually for emergency cesareans where an epidural is not an option.

Under general anesthesia, you are not awake and cannot see, feel or hear anything during the birth. Just over 5% of cesarean births use general anesthesia. General anesthesia typically uses a sedative such as propofol or ketamine and a muscle relaxant. During this procedure, you are intubated. This means that you have a tube inserted into your airway and are placed on a ventilator. When you are intubated in an emergency cesarean, the risk of aspiration is the reason eating during labor has historically been discouraged. During the emergency cesarean, you are continuously breathing in a gas anesthetic. The types of narcotics used provide amnesia, so you have no memory of the procedure and immobilization, so you cannot move. The effect is that you are unconscious.

An anesthesiologist performs general anesthesia, and this is only available in an operating room at a hospital. Again, this is only used in emergency scenarios when necessary. The vast majority of cesarean births are with an epidural that allows the mother to be awake during birth. This is not something you would opt for in your birth plan. If you have questions or concerns about general anesthesia, please talk to your doctor or midwife.

Local Anesthetic Injection

A local anesthetic injection is a shot of pain-relieving medication to a specific area. This is routine before performing an episiotomy or repairing a tear to your perineum or vagina.

An episiotomy is a surgical incision your care provider makes with either a scalpel or scissors in the second stage of labor to help your baby be born. Your care provider could also use a local anesthetic with an assisted delivery. A study showed that in a forceps delivery, an episiotomy decreases the risk of perineal tears of all degrees. One study shows since 2006, rates of episiotomy have decreased to around 11.6% of vaginal births. This rate varies greatly depending on the hospital. Of the top 10% of hospitals that used episiotomy most frequently, the mean adjusted episiotomy rate was 34.1%.

Even if you do not have an episiotomy, it is very common to tear your perineum during birth. This study shows the rates of tearing with a first baby are 90% and decrease to 69% in subsequent births. According to the American College of Obstetricians and Gynecologists, the rate of some type of laceration during all vaginal births is between 53-79%.

Medications, Prevalence, and Availability of Local Anesthetics

The most commonly used pain medication for a local anesthetic is lidocaine. You could also receive various medicines that are similar and administered the same way. A local anesthetic is available in all birth settings, including by a midwife in home birth.

How a Local Anesthetic Works and What to Expect

A local anesthetic works by binding to the sodium channel in cells and blocking nerve signals to your brain. You may still feel pressure, but you should not feel pain in the area where the anesthetic is injected. If you require a local anesthetic, you will receive a shot of medication in the needed area. You may feel a pinch from the needle, and the medication will go to work quickly. Depending on your needs, you may have multiple injections.

Local Anesthetic Benefits and Effectiveness

If you are having an episiotomy or need a tear repaired with stitches, there is no reason you should feel pain during these procedures. Even if you are planning an unmedicated birth, this is something you would incorporate if needed. 

Local Anesthetic Side Effects

Local anesthetics are common in all medical settings and generally do not have side effects. In rare cases, you could have an allergic reaction or nerve or heart problems if the dose is too high. Since this is a standard procedure, you should trust that your care provider is skilled in performing local anesthesia. There should be no adverse effects on your baby. The main feature of a local anesthetic is that the medications remain localized to a specific area. If you receive this to repair a tear, the injection occurs after your baby is born.

Thank you to Zahler for their support of this episode.

Zahler makes a high-quality prenatal vitamin that has the active form of folate plus omega 3s and DHA. This is my favorite prenatal vitamin, the one I take every day, and my #1 recommendation. Zahler is offering an exclusive discount to listeners of the Pregnancy Podcast. To check out the vitamin and get the promo code to save 20% when you buy a one-month supply on Amazon click this link Zahler Prenatal + DHA.