Your Pregnancy Matters

Nitrous oxide for labor: Seriously, don’t laugh before you read this

Your Pregnancy Matters

Nitrous oxide, or laughing gas, works by relieving anxiety rather than removing the sensation of pain.

We’ve all heard of nitrous oxide, or “laughing gas.” Usually we think of it in the context of dental procedures, but did you know nitrous oxide has a place in labor and delivery? It’s true – nitrous oxide for labor analgesia (pain relief during labor) has been around for over 50 years.

The first recorded use of nitrous oxide was in Poland in 1881. Since the development of the delivery system in the mid-1900s, it has been continually available for use during labor in the UK and other Western countries and has remained a popular option among laboring mothers there.

Nitrous oxide has been used in the US, as well; however, with the development and ensuing popularity of neuraxial anesthesia (popularly referred to as an epidural) in the 1970s, interest in nitrous oxide waned in the United States and was abandoned on most labor and delivery units. In some areas of the country, however, nitrous oxide has been continually available and remains a popular option.

In the past decade, American interest in using the gas during labor has been on the rise. Let’s learn more about nitrous oxide as an option during labor.

What is nitrous oxide?

Nitrous oxide (N2O) is a nonflammable, colorless gas. Although generally considered odorless, there is a faintly pleasant sweet sensation when inhaled. Nitrous oxide does not actually reduce pain or take away the sensation of a contraction, like an epidural. Instead, it relieves anxiety, which helps in the tolerance of pain.

If you have ever had a dental procedure, you may recall that you still felt the needle when the dentist administered the local anesthetic; you probably just didn’t feel like you cared about it as much as you would have without the gas.

In the U.S., the NITRONOX® system has FDA approval for delivery of a stable 50/50 mix of nitrous oxide and oxygen. The gas is self-administered via a facemask you hold in place. When you inhale, a valve allows the gas to be released, and when you exhale the system has a separate scavenging tube that captures the exhaled gas and prevents it from being released into the room and affecting the people around you. The effects clear quickly when you resume breathing room air.

Reported side effects include a floating or “cloud 9” sensation, which can lead to vertigo. Some people experience nausea, but it is not associated with increased vomiting during labor. There are no effects on uterine activity or fetal heart rate, and nitrous oxide does not result in sedation of the newborn.

The American Society of Anesthesiologists classifies nitrous oxide as “minimal sedation” because the user remains responsive and maintains control of her own airway and ventilation and cardiovascular function is not impaired.

How do you use nitrous oxide during labor?

Anecdotal reports suggest nitrous oxide works best when women start breathing it in about 30 to 60 seconds before their next contraction so the peak effect of the gas occurs during the peak of the contraction. This is not an exact process, especially in early labor when contractions may not be regular or predictable. Studies have shown nitrous oxide has an analgesic effect similar to short-acting patient-administered narcotics, such as an IV PCA pump.

Nitrous oxide can be used during any stage of labor or after the delivery if there is need for repair of a laceration or manual extraction of retained placenta. Because the effects wane so quickly, converting to another form of anesthesia can be done without delay. Nitrous oxide can even be used during epidural placement.

The American College of Nurse Midwives, in a 2009 statement, advocated for availability of the gas and recommended that, when available, midwives be trained to oversee its safe use. The American College of Obstetricians and Gynecologists has not issued a statement regarding the use of nitrous oxide in pregnancy.

Who would be a good candidate for nitrous oxide during labor?

Nitrous oxide has many benefits and few contraindications (your doctor will go over those if you ask about using it). It can be initiated quickly, making it a great choice for women in advanced labor who just need a little help to get through delivery.

The rapid onset and clearance are also great features for women who labored without analgesia but need a post-delivery procedure.

Ok, I’m not laughing anymore, but what else should I take into consideration?

Because nitrous oxide has to be administered via facemask, it’s probably not the best option if you struggle with claustrophobia. For safety reasons, the facemask cannot be secured with a strap or any other device that holds it in place. If you present in early labor with your first pregnancy, it may be a long time until delivery. While not contraindicated, having to use the mask over and over for many hours may get tiring. Due to risk for fall, as well as the obvious need to be close to the mask, you cannot use nitrous oxide while walking or moving around during early labor.

Because nitrous oxide is cleared via the lungs, it’s also not recommended for women with severe chronic obstructive pulmonary disease (COPD) or any severe upper airway obstruction (this does not include mild asthma). Women known to have B12 deficiency or pernicious anemia, as well as those known to have an MTHFR gene mutation, should not use nitrous oxide in labor. While nitrous oxide has been used for years in Europe with no observed immediate effect on the newborn, there are no long-term studies.

My best advice would be to start with the hospital where you plan to deliver. Although nitrous oxide is becoming more popular and available, it is still not widely available in the Dallas area. If it is an option at your delivery facility, discuss it ahead of time with your OB or CNM because they know you best.

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