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Overview

Nitrous oxide, commonly known as laughing gas, was first used as a labor analgesic in 1881. Over 50% of births in Finland, Norway, England, Australia, and New Zealand, 60% of births in the United Kingdom, and 70% of births in Sweden involve nitrous oxide. It is less common in the United States, and this is changing as it is becoming more widely available in both hospitals and birth centers. Many mothers incorporate nitrous oxide in their plan for a natural or a low-intervention birth. Using nitrous oxide induces feelings of euphoria and creates a disassociation with the discomfort and pain of contractions. This episode explains everything you need to know about nitrous oxide and the risks and benefits of using it during labor and birth.

Article and Resources

Most people think of an epidural when thinking about pain medication for birth. Epidurals are the most widely used, but there are other options. This article focuses on the pros, cons, and evidence of nitrous oxide for relieving pain during labor and birth.

Natural Birth

Natural birth typically describes a birth without pain medications or interventions. In recent years there has been some criticism that all births are natural and that utilizing pain medications or other interventions does not make birth unnatural. The majority of parents who choose a low intervention or non-medicated birth do so because they do not want to interfere with the natural process your body goes through during labor. If there were a solution that prevented labor pain without any adverse side effects, everyone would use it. Unfortunately, this does not exist. Any intervention or medication comes with both risks and benefits.

Epidural

Epidurals are the most widely used intervention for relieving the pain of contractions and labor. For the most recent year data on epidural use is available (2016) 73.5% of mothers used an epidural during labor. Epidurals are available in all hospitals in the United States and are not an option if you opt for a home birth or a birth center. You have many choices for the interventions and tools you utilize during labor and birth. It is not a black and white choice between an epidural in a hospital or home birth with zero interventions.

Nitrous Oxide (N2O)

Nitrous oxide is a nonflammable, tasteless, odorless gas. It is commonly known as laughing gas. This is an anxiolytic and decreases anxiety to help you be more relaxed. It is unlikely inhaling nitrous oxide will make you laugh.

Recreational use of nitrous oxide is associated with severe adverse effects. This is commonly known as whippits. This is the stuff you can get from a can of whipped cream. We are only talking about nitrous oxide in terms of the concentrations and frequency used during labor under a medical professional’s care.

Concentrations of Nitrous Oxide Used in Labor

The first use of nitrous oxide as a labor analgesic was in 1881. The nitrous oxide used during labor is a blend of 50% nitrous oxide and 50% oxygen. This is different than the nitrous oxide commonly used in dentist offices, which allows for a higher concentration of nitrous oxide, up to 70%. In a dental setting, nitrous oxide is often continuous, with a mask strapped to your face while continuously breathing it. During labor, the use of nitrous oxide is intermittent.

Prevalence and Availability

Over 50% of births in Finland, Norway, England, Australia, and New Zealand, 60% of births in the United Kingdom, and 70% of births in Sweden involve nitrous oxide. In the United States, the use of nitrous oxide has decreased with the rise in epidural use since the 1970s. Although it has not been widely available, access to nitrous oxide during labor is expanding in hospitals and birth centers. If your hospital or birth center does not have laughing gas available, it never hurts to ask if they can get it. More requests for nitrous oxide could help to increase the availability of these options for future moms.

The American College of Nurse-Midwives has an official position statement, noting that women should have access to a variety of measures to assist them in coping with the challenges of labor. Among these should be nitrous oxide analgesia, which is commonly used in many other countries.

Even if your hospital or birth center has nitrous oxide available, they may be restricting its use due to COVID-19. The concern is that COVID-19 spreads through the air. There are questions about the cleaning, filtering, and potential aerosolization of nitrous oxide in the setting of COVID-19. Hopefully, it can be available, especially in cases where the expecting mother is negative for COVID-19. According to the American College of Obstetricians and Gynecologists, labor and delivery units may consider suspending the use of nitrous oxide for individuals with suspected or confirmed COVID-19. For patients with a diagnostic test for COVID-19 confirmed negative, nitrous oxide may continue to be offered as an option for analgesia.

Contraindications

The majority of expecting mothers are candidates to use nitrous oxide during labor. There are a few contraindications for using nitrous oxide.

If you have had a collapsed lung or gastric bypass, you should not use nitrous oxide. Both of these conditions can lead to air pockets that nitrous oxide can expand.

If you had recent inner ear surgery, nitrous oxide could cause pressure changes in your ears.

If you have a severe B12 (cobalamin) deficiency, your care provider would not recommend nitrous oxide. This is unlikely if you are eating well and taking a prenatal vitamin. If you are vegetarian or vegan, you should be paying particular attention to ensuring you are getting adequate B12 from a supplement. The use of nitrous oxide inactivates B12 and can cause a B12 deficiency.

Nitrous Oxide and MTHFR Polymorphisms

There have also been concerns raised about nitrous oxide if you have an MTHFR mutation. An MTHFR mutation is a genetic mutation that affects a large percentage of the population and impairs enzyme function, impacting your health. Dr. Ben Lynch, an expert on MTHFR, advises against nitrous oxide, and you can read more on his site here.

One study found that patients who had an MTHFR gene polymorphism were at a higher risk of developing hyperhomocysteinemia after nitrous oxide anesthesia. This condition is when you have high levels of homocysteine, which can contribute to damage to your arteries or blood clots. This study used a concentration of 66% nitrous oxide over two hours, which differs from the levels nitrous oxide is used during labor and birth. If you have any questions about your MTHFR status and using nitrous oxide, please bring it up with your doctor or midwife.

How Nitrous Oxide Works

Nitrous oxide works by increasing endorphins, dopamine, and other natural opioids in the brain while also decreasing the release of cortisol. The mechanism of action of nitrous oxide is not established or completely understood. Inhaling this gas induces feelings of euphoria. In labor, it can create a disassociation with the discomfort of contractions. It doesn’t numb pain, as drugs in an epidural do. Nitrous oxide changes your perception of the pain from contractions rather than blocking or numbing the sensation.

What to Expect with Nitrous Oxide

Nitrous oxide can be used at any stage of labor and can be started or stopped anytime. It is self-administered, meaning you hold a mask to your face and decide when and how much to inhale. To use nitrous oxide, you have to hold the mask or mouthpiece to your face, and no one can do this for you. Excessive inhalation can lead to drowsiness, which is why the mask is not continuously attached to your face, and no one can hold it to your face. With the mask held to your mouth, you breathe in, and the gas is released.

The key to making this as effective as possible is to time your inhalations to coincide with contractions. Nitrous oxide takes effect 30-40 seconds after inhalation. The benefits dissipate quickly, within a few minutes of discontinuing inhalation. Ideally, you want to get in a rhythm of inhaling about 30 seconds before a contraction. This may take some practice through several contractions to get the timing and rhythm down. You also exhale into the mask to minimize nitrous oxide exposure to other people in the room.

Nitrous Oxide Benefits 

There are some benefits and advantages of nitrous oxide. You can start or stop at any time during any stage of labor. If you choose to use nitrous oxide, then decide you want an epidural, you can do that. Some women opt for nitrous oxide to help with anxiety or discomfort while an anesthesiologist is administering an epidural. In one study, 69% of participants converted to another analgesic method during labor when they started with nitrous oxide. Those who used labor induction, oxytocin augmentation, and labor after cesarean were more likely to convert to another method. (This study is one of the most recent comprehensive studies on this topic and is cited in several places in this article.)

You are not confined to a bed and should be able to maintain your mobility. However, you will need to remain near the nitrous oxide to access it through your mask. You should not be required to have continuous electronic fetal monitoring, giving you some mobility and freedom to move around during labor. Continuous monitoring usually accompanies an epidural.

Nitrous oxide does not affect oxytocin production, so it should not slow down labor.

Nitrous Oxide Effectiveness

A study of 463 women who used nitrous oxide rated satisfaction on an 11 point scale from 0-10, with ten being very satisfied. The mean score was 7.4. 69% converted to another type of pain relief during labor, with the majority converted due to inadequate pain relief.

The effectiveness of nitrous oxide or any intervention depends on what your goal is. An epidural may be a better option for someone who desires to feel no pain or discomfort during labor. If you want a less invasive alternative to take the edge off, nitrous oxide may be worth exploring.

Nitrous Oxide Side Effects

Nitrous oxide has a lower list of side effects than other interventions like an epidural or a spinal block. Some women find the sensation of breathing into a mask during contractions to be unpleasant. This could be an issue, especially if you are claustrophobic. In this study, the most commonly reported side effects were nausea (3.7%) and dizziness (1.7%). Fatigue may occur when used for prolonged periods, and this would apply if you use it throughout a long labor. 3 (0.7%) participants reported drowsiness.

There may be some concerns about prolonged exposure to health care workers who are consistently in the presence of nitrous oxide, but none of this research pertained to a mother in labor. Also, many of these studies are from decades ago. Today, more safety measures, like adequate ventilation, are used. If you are a healthcare worker or work in a dental office, you may have frequent exposure to nitrous oxide. This is a topic you may want to explore further or talk to your doctor or midwife about the safety of your exposure during pregnancy.

Effects on Hormones

Nitrous oxide does affect endorphins, prolactin, cortisol, epinephrine, and norepinephrine. For more details on hormones and how they work in birth without interventions, see this episode. Nitrous oxide does not affect oxytocin, which is the hormone that drives contractions. It is tough to tease out how much using this gas affects each hormone and how that potentially impacts labor and birth, and there is no research examining this.

How Nitrous Oxide Affects Your Baby

Nitrous oxide is often talked about in terms of not having effects on your baby. In the study of 463 participants, 97.8% of babies had an APGAR score of 7 or higher at five-minutes. This study does note that more studies are needed, particularly on long-term neonatal effects.

A review found that Apgar scores in newborns whose mothers used nitrous oxide did not differ significantly from newborns whose mothers used other labor pain management methods or no analgesia.  In this review, two studies were good quality, 11 were fair, and 46 poor.

Overall, it is promising that the research available does not show adverse effects, and hopefully, in the future, we will see more evidence of safety. None of the studies reviewed for this episode examined impacts on breastfeeding.

 

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