Nitrous Oxide for Labor Pain

Nitrous oxide (also called “laughing gas” or “gas and air”) has long been in common use for labor pain in other countries, being used by more than half of laboring women in such countries as England, Finland, Sweden, and Canada. It has not been common in the United States in recent decades (it was only available at 5 hospitals in 2012); however, its popularity is now increasing as equipment becomes more widely available, and may soon be seen in more hospitals and out of hospital birth centers. This online article is intended as a supplement to chapter 13 of the 2016 edition of Pregnancy, Childbirth, and the Newborn which does not cover nitrous oxide.

How Administered

Nitrous oxide is a gas. It is mixed 50/50 with oxygen, and inhaled through a mask. (Note: If you’ve had nitrous at the dentist, that’s a 70/30 or 80/20 mixture. So the dose given in labor is lower than the dose at dental procedures, and has a milder effect.) The laboring mother holds the mask to her face whenever she wants a dose. The gas only flows when she inhales. When she moves the mask away, the medication stops. (To see what the equipment looks like in use, do an online image search for “nitrous oxide in labor.”)

The peak pain relief effect kicks in about 50 seconds after you start inhaling. But the peak intensity of contraction pain tends to be 25 – 45 seconds into a contraction. That means you need to start inhaling 30 seconds BEFORE the next contraction is expected so the gas is in full effect when the contraction pain peaks. It can be tricky to get timing just right.


Nitrous oxide stimulates the brain to release endorphins and dopamine, hormones that help to reduce pain. Nitrous oxide does not completely relieve labor pain, but women are less bothered by the pain. It reduces anxiety, and can cause a mildly euphoric feeling. Women describe themselves as feeling relaxed and calm while using it. Women report that they liked the fact that they had control over the administration. (To learn more about the laboring person’s experience of nitrous, watch this video from Vanderbilt at

Other benefits are that it’s inexpensive (at some hospitals, there’s no extra charge – it’s included in room cost), it takes effect quickly, and if you stop using it, the effects fade quickly (it has a half-life of 3 minutes) rather than remaining in your system for a long time. That means that if you decide nitrous does not provide enough pain relief, it’s easy to move on to other options, such as epidural analgesia.


One study (Pasha, 2012) found that 92% of women had less pain with nitrous than without. They were also less likely to have severe pain. On nitrous, 41% reported severe pain and 10% reported very severe pain. In the no-nitrous group, 55% had severe pain and 27% had very severe pain.

It’s important to note that nitrous oxide is a mild pain reliever. You should not expect it to take away all your pain. An epidural is much more effective at that; however, an epidural also has more tradeoffs and side effects, so you may choose to start with nitrous and see if that offers enough relief. Some nurses describe the choice to have nitrous as “why not try it and see if it helps.”

Rather than thinking of nitrous as pain relief, it may help to think of it as a ‘coping boost.’ One study showed that it did not reduce the intensity of pain much (as measured on a visual analog pain scale), but after the study period, when given the option to stop using it, women wanted to continue using it anyway. (Carstinou, 1994) The unpleasantness of the pain was reduced, and seemed more manageable. Another study found that 98% of users were satisfied with the experience of using nitrous oxide. (Pasha, 2012) Studies also show that women say they would use it again in a subsequent labor.


Unlike epidural analgesia, nitrous does not require extra procedures or extra monitoring. You will not need an IV or continuous fetal monitoring. You are also able to stand, move, and change positions. (If the oxygen comes from a portable tank, you can move around with it, but if the oxygen is piped in from the wall, you’ll need to stay near the bed.)

Possible Side Effects

Side effects on mother and baby are minimal, and less than those experienced with epidural analgesia and with IV / IM narcotics. They can include nausea, dizziness, drowsiness and a hazy memory of events. There is a small chance you could lose consciousness, but if you do, you drop the mask away from your face, and quickly recover. Nitrous does not slow labor and does not affect your ability to push. It does not appear to affect baby at birth. The portable pump is loud, but nurses report this does not seem to bother the user.

Nitrous is contra-indicated if you have persistent anemia / vitamin b12 deficiency.

Timing in Labor

Can be used at any time in labor, except you cannot have nitrous if you have had narcotics in the past two hours. You must wait for them to wear off.

Some cases where it might be especially helpful: during transition, during anxiety provoking procedures (such as vaginal exams, IV starts, stitches for a tear), for women who arrive at the hospital in heavy labor and need quick relief, and at any time by someone who wants to delay getting an epidural. Birth center midwives also report using it when a mom is considering a transfer to the hospital for pain medication. Anecdotally, they say that about half the time it has allowed the client to remain at the birth center.

Comparison to Other Methods

On page 211 – 212 of the book, we offer a chart called “Nonmedicated Labor versus Medicated Labor” that compares what labor is like if no pain medications are used, or if IV narcotics or epidural analgesia are used. Here is that same information for nitrous oxide, so you can easily compare and contrast to the other options.

Pain-Relief Option Used Nitrous Oxide
How it affects your experience of pain Increases pain-relieving endorphins, eases anxiety or fear, and enhances your mood. Small decrease in pain intensity, but makes pain less unpleasant. Can boost your ability to cope.
Feedback from women who used it “Labor was still intense, but it took my fear away and helped me calm down. It made it seem like coping with the pain was doable.”
How it affects your mental state You’re relaxed, calm, may be drowsy or light-headed.
How it affects your mobility You can walk, move around and change positions. If the equipment is hooked up to the wall (rather than being on a mobile cart), you will have to stay close to the bed.
What you’ll need from your support people You’ll still be experiencing pain (though you’ll be less distressed by it). You’ll still want support with comfort techniques and emotional support. Also, they can tell you when a contraction is about to start so you can begin inhaling. (Nitrous oxide is most effective if you start 30 seconds before the contraction.)
Equipment and precautions required You’ll hold the mask that dispenses the nitrous, inhaling from it as desired. Some women need an oxygen sensor on their fingers.
Impact on labor progress Does not affect labor progress.
Timing Can be used at any time, especially during anxiety provoking times in labor.
Availability Very limited availability in the U.S.
Possible risks to you Minimal. (See above.)
Possible risks to baby No apparent risks
Cost Inexpensive
Best option for you if… You just need a little boost to your ability to cope, or need to reduce your anxiety.

For more information:

Source for study data cited: Pasha, et al. Maternal expectations and experiences of labor analgesia with nitrous oxide. Iran Red Crescent Medical Journal, 2012.


Labor Hormones in under 10 minutes

Note: this page is about how professionals can TEACH this concept to expectant parents. If you’re an expectant parent looking for info on labor hormones, their effect on labor pain, and what your partner can do to help you have a shorter and less painful labor, click here.

In my childbirth classes, and with doula clients, I want them to understand that our emotions, and the support we receive, absolutely affect labor on a physiological basis, by influencing our hormones. The big message is that fear and anxiety slow labor down and make it more painful. Support and feeling safe make labor faster and easier. I have simplified the complex details into a simple stick figure drawing that takes 5-10 minutes.

Before I talk about my teaching method, let’s start with a basic summary* of hormones

Hormone What Does It Do What doesn’t help What does help
Oxytocin Causes labor contractions that dilate cervix Anxiety, bright lights, feeling observed, feeling judged

Pitocin – if have synthetic oxytocin, make less hormonal oxytocin

To increase oxytocin: Skin-to-skin contact.
Nipple stimulation, making love.To increase endorphins: social contact and support from loved ones.To increase oxytocin and endorphins and to reduce adrenaline: create an environment where we feel private, safe, not judged, loved, respected, protected, free to move about.(So, partners, if you remember nothing else about labor support, remember that if she feels safe, loved and protected her labor will be faster, and less painful)
Endorphins Relieve pain, reduce stress (cause euphoria and feelings of dependency) Stress, lack of support

Narcotics (if you have an external opiate, your body will start producing less internal opiate… even after the narcotics wear off, you’ll have less endorphins)

Catecholamines (adrenaline, etc.) In early / active labor: slow labor down(Imagine a rabbit in a field. If it doesn’t feel safe, it wants to keep baby inside to protect it)

In pushing stage: Make you and baby alert and ready for birth, give you energy to push quickly.
(If the rabbit is about to have a baby, and something frightens it, it wants to get the baby out as quickly as possible so it can pick it up and run with it.)

Stress / anxiety / fear

Lack of control

Feeling trapped

Hunger, cold


So, in class how do I convey these ideas in just a few minutes, so it’s easy to understand and to remember?

First, I say: “In labor, our emotions and our environment effect our hormones. Our hormones have a huge effect on labor. Let’s look at a couple scenarios for labor.” [I draw two stick figures on the board.] “This one is awash in stress hormones which will make labor longer and more painful. Let’s label it adrenaline. This one is under the influence of oxytocin and endorphins. These help the laboring person shift into an altered state where labor pain is milder (less intense and less unpleasant) and also help labor progress more quickly.” [Add labels to drawings, add sad face and smiley face.]


Then I say “So, you are all probably familiar with adrenaline. What do we call it? Yes, the fight or flight hormone. This is the idea that if an individual ran into a tiger in the woods, they would choose either to fight it or to run away. Do you know what we call oxytocin? Many call it “collect and protect” or “tend and befriend.” If a tiger is coming into our village, we gather everyone together, because we are safest together.” [I add these labels to my drawing.]  (I sometimes throw in the tidbit here that men who are not dads are more likely to release adrenaline during stressful situations; women and dads are more likely to release oxytocin – it’s the “gather the babies and protect them” response.)


“So, what effect do these hormones have?”

“With adrenaline, all your muscles tighten. All your energy goes to your limbs in case you need to fight or run away. So, oxytocin production drops and labor slows down. (It’s hard for your cervix to open when you feel scared…)  You are also more sensitive to pain – this is useful if you’re at risk of injury – your body tells you what to move away from. But, in labor it’s not helpful – it just means labor hurts more!”

“With oxytocin and endorphins all your muscles relax. Energy is sent to the uterus and oxytocin increases. (Oxytocin is often called the love hormone, because it increases when we feel loved, and its peak levels are when we orgasm, when we birth, and when we breastfeed. It’s all about making babies, birthing babies, and feeding babies.) We also get an increased endorphin flow, which makes us less sensitive to pain, can cause euphoria, and can cause feelings of love and dependency in us… “I love you man….””

[As you talk, write the notes, and draw on the figures like this to show effects…]


[If you teach the 3R’s method for coping with labor pain – relaxation, rhythm, and ritual, you can also add in here: If you’ve got oxytocin and endorphins flowing, you may also have more rhythm – you may rock, moan or sway rhythmically. If your partner helps to reinforce your ritual, it will help build your oxytocin and endorphins.]

“So, what causes adrenaline rushes? Fear, anxiety, feeling watched or judged, feeling like you have no control over your situation, being hungry or cold.”

“How can we tell a person in labor is rushing adrenaline? They act vigilant or panicky, have lots of muscle tension, and a high pitched voice.”

“What causes oxytocin and endorphins to flow? Feeling safe, loved, protected, having privacy, having support, eye contact, skin-to-skin contact, and love making.”

“How can we tell if someone is in an endorphin / oxytocin high? They seem open and trusting, their muscles are relaxed, and their voices are low-pitched and husky.”

[Add notes about causes and signs to your picture.]


“So, partners, what’s the big picture summary?”

“If you remember nothing else from this class, remember this: If a person in labor feels safe, loved, and supported, her labor will be faster and less painful. If in doubt about what to do, always return to this! Anything that helps her relax, gain her rhythm and feel cared for will help her.”

More Info

* If you want a great overview of hormones in labor, read Pathways to Birth. If you want all the details on hormones in labor, read Hormonal Physiology of Childbearing. You can find them both at:

To read more of my blog for childbirth educators and doulas, click here. For lots of ideas for interactive activities for childbirth education classes, click here. To learn more about any topic related to the perinatal period, check out our book Pregnancy, Childbirth, and the Newborn: The Complete Guide.

Pain Med Preferences

In classes, we talk about the Pain Medication Preference Scale from Pregnancy, Childbirth, and the Newborn. We have the expectant parents look at it together, and then encourage the pregnant parent to choose the number that best represents their preferences, and the support partner to choose what they WISH the pregnant parent would choose.

Then we have them discuss. Often they align, but not always. Sometimes there is a pregnant parent who is hoping for an un-medicated labor who has a partner who can’t bear the idea of seeing them in pain. Sometimes a pregnant parent wants medication, but the partner has concerns about side effects on them or the baby. I would much rather this issue come up during pregnancy when they can resolve it rather than arising without warning in labor.

I have designed a new worksheet that asks more questions about labor coping preferences that they can fill out separately, then discuss, to further illuminate these issues and enhance the discussion they can have about goals and preferences before labor begins. You can see the Pain Preferences Worksheet here – feel free to print and use in class.

Research Summary on Effectiveness of Non-Drug Coping Techniques

There have been several literature reviews of available research on the available non-pharmacological techniques for coping with labor pain. Each of these reviews acknowledges the limitations of the research that they compile: primarily the studies are small sample sizes, and are not properly randomized control trials. (Women are typically allowed to choose which coping techniques to use with their labor.) So, all conclusions come with the caveat that “more research is needed.”

This chart summarizes those reviews. (Note: the birth ball results are based on a single study rather than a review.) Pain coping techniques are compared to “usual care.”

The chart compares the following factors that might be desired outcomes coping measures: less pain intensity, less likelihood that the laboring mother will turn to pain medications (unless that was her goal), higher satisfaction with pain relief, shorter labor, higher chance of spontaneous vaginal delivery (vs. instrumental delivery or cesarean), and less use of Pitocin to augment a slow labor.

Source Less pain? Less pain meds? More satisfaction Shorter labor Spontan. vaginal Less pitocin
Acupressure yes *
Acupuncture yes yes
Acupuncture yes yes * yes * yes *
Aromatherapy NSD
Aromatherapy NSD NSD NSD NSD
Birth Ball yes * NSD
Continuous Support yes yes yes yes yes
Epidural & Pain Meds yes N/A yes no no no
Hypnosis yes * NSD NSD yes * NSD
Hypnosis yes yes yes yes
Immersion in Water yes NSD
Massage yes
Music / audio NSD NSD NSD
Positions & Movement yes yes yes
Relaxation yes yes yes
Sterile Water Inj. yes NSD
Sterile Water Inj. yes yes
TENS yes * NSD
Yoga yes yes yes

* means limited data; NSD means there may have been a difference, but it wasn’t statistically significant

(Note: In a 2014 review by Chaillet, et al, these techniques were pooled into 3 categories, which helped to increase the statistical significance of the findings. Learn more. Also check out more articles about coping with labor pain.)

New Ways to Talk about Labor Pain V: Research on Effectiveness of 3 Mechanisms


In 2012, a new Cochrane review of pain management for women in labor was released. Although it had positive things to say about the non-pharmacological techniques, it also said that research into their efficacy was unclear due to limited evidence…

“WHAT WORKS: Evidence suggests that epidural, combined spinal epidural (CSE) and inhaled analgesia effectively manage pain in labour, but may give rise to adverse effects. … WHAT MAY WORK: There is some evidence to suggest that immersion in water, relaxation, acupuncture, massage and local anaesthetic nerve blocks or non-opioid drugs may improve management of labour pain, with few adverse effects.  Evidence was mainly limited to single trials. …INSUFFICIENT EVIDENCE: There is insufficient evidence to make judgements on whether or not hypnosis, biofeedback, sterile water injection, aromatherapy, TENS, or parenteral opioids are more effective than placebo… Most methods of non-pharmacological pain management are non-invasive and appear to be safe for mother and baby, however, their efficacy is unclear, due to limited high quality evidence.”

A 2014 review by Chaillet, et al (Chaillet, et al. (2014) Nonpharmacologic approaches for pain management during labor compared with usual care: a meta-analysis. Birth, 41(2): 122-37. is a significant addition to the research about non-drug approaches.

Chaillet, et al pooled techniques into three categories. If you’ve read my posts from the past few days, you’ll be familiar with these concepts. Also, see the chart at the top of this post for more information.

  • Gate Control mechanism = apply non-painful stimuli on the painful area. Methods included massage, bath, positions, walking, and birth ball. The theory is that this will block some of the intensity of the pain.
  • Diffuse Noxious Inhibitory Control (counter-irritant) = create pain or discomfort anywhere on the body. Methods included acupressure, acupuncture, TENS, sterile water injections. The theory is that this discomfort causes the body to release endorphins which reduce pain intensity.
  • Central Nervous System Control (cognitive/support techniques). Methods included  attention focus, education, relaxation, hypnosis, continuous labor support.

By pooling studies together, you get larger sample sizes which increases the statistical significance of the results. Note, all techniques were compared to “usual care” which might have ranged broadly depending on the preparation of the laboring family and the support they were given by caregivers. It is possible that some in the “usual care” groups were also using a variety of coping techniques. So, the true difference between people who use some coping techniques and those who use none may be even greater than these results indicate.

The results of this review were:

  • Gate Control mechanism. Those who used these techniques had lower pain intensity (as predicted), were less likely to use epidural, and needed less Pitocin.
  • Diffuse Noxious Inhibitory Control (counter-irritant). Those who used these techniques had lower pain intensity, were less likely to use epidural, and more satisfied with birth. (Two trials found women felt safer, more relaxed, and more in control.)
  • Central Nervous System Control (cognitive/support techniques) Those who used these techniques were less likely to use epidural, Pitocin, less likely to need instrumental delivery or cesarean, and had a higher satisfaction with birth. The CNSC did not reduce the intensity of the pain so much as they reduced the unpleasantness of the pain. (See more on intensity and unpleasantness here.) So, although labor still hurt a lot, women felt better able to cope – more like they were working with labor pain.

The most effective technique overall was continuous labor support, such as that offered by a doula. The effectiveness of support was already demonstrated in a Cochrane review by Hodnett et al, (Hodnett E, Gates S, et al.. Continuous support for women during in childbirth. Cochrane Database Syst Rev. 2013. CD003766)

The best results in pain coping were from combining the labor support and education which reduce the unpleasantness of pain with gate control or DNIC techniques that reduce the intensity of the pain.

Recommended: be sure to also check out Henci Goer’s discussion of this study on Science and Sensibility.

New Ways to Talk about Labor Pain, IV: Bonapace Method

The Bonapace Method for reducing pain during childbirth can be used instead of, or in conjunction with, a traditional childbirth education class.

This method does not just teach pain coping techniques, but also teaches about the role of labor pain, how pain messages are transmitted in the body, and three mechanisms that help moderate the perception of pain. Those mechanisms are:

Cognitive structuring / central nervous system control (CNSC). Understanding labor pain and progression – what’s happening and why – enhances a sense of self-control. Focusing on something positive (like a self-affirmation) helps with labor pain.

Gate ControlTheory. Non-painful stimulation blocks part of the pain message transmitted by the spinal cord. Note: Bonapace interprets this differently than I have see elsewhere, saying specifically that it is pleasant sensation applied where the pain is located. The description on their website says “To activate this mechanism during childbirth, the fingers must be run lightly over the painful area, particularly during contractions.”

Diffuse Noxious Inhibitory Control (DNIC). (I call this counter-irritation) Creating a second pain elsewhere on the body (i.e. not where you’re already hurting). The brain wants to reduce the pain’s effect on the body as a whole, so releases endorphins to do so. But the sensations near the second pain are still felt because the body is assessing them. (So, under this theory, holding a birth comb tightly causes a release of endorphins which helps with the labor pain, but the user is still aware of the pressure points from the comb on their palm.) In the Bonapace method, sensitive points on the body (trigger areas) are massaged by the partner, causing pain.

In a journal article (“Evaluation of the Bonapace Method: a specific educational intervention to reduce pain during childbirth”, J Pain Res 6: 653-661 at, Bonapace et al, compare the results of a “traditional childbirth training program” (TCTP) with the Bonapace method. Study participants chose which class to take from these options.

The TCTP was a 4 week class, with a total of 8 hours of class time, started around the 23rd week of pregnancy. It covered A&P of childbirth, exercises, stages of labor, variations, pain meds and newborn care. Relaxation, visualization, massage, and labor positions were not taught. Only breathing techniques were practiced.

The Bonapace class was 4 weeks, 8 hours, starting in the 30th week. The entire program was dedicated to pain management and partner participation. It covered 1) CNSC through breathing, relaxation, and cognitive understanding of labor pain and endorphins, 2) Gate control – non-painful stimuli such as walking and light back massage between contractions, and 3) DNIC where the partner did painful massage of acupuncture triggers points in the lower back, hands, and buttocks.

39 women participated in the full study. In labor, every 15 minutes, participants were asked to rate their pain on two scales: intensity and unpleasantness. (If pain medications were given, they stopped assessing pain after the medication. If that participant had pain scores for two phases of labor, they were kept in the study, if not, they were dropped.

Those who had learned the Bonapace method had an average of 45% less pain intensity and 47% less unpleasantness than those who had received the “traditional” childbirth education. No difference was found in the use of pain medication.

The reduction in intensity of pain was consistent for nulliparous and multiparous parents. On the “unpleasant” ratings, there was a larger reduction in scores for nulliparous than multiparous. This is likely due to anxiety… a nulliparous woman with no birth experience and no training / childbirth preparation is likely to be anxious about labor pain (and, of course, anxiety increases pain). With the TCTP, her anxiety may have been somewhat reduced and thus her pain unpleasantness would be reduced, but with the Bonapace method, her anxiety and thus unpleasantness were much more reduced.

This study indicates that being given information about the physiology of pain, and plenty of education in clear, simple techniques to manage it, has a significant impact on pain intensity and pain coping.

New Ways to Talk about Labor Pain III: Diffuse Noxious Inhibitory Control

Diffuse Noxious Inhibitory Control (DNIC) is one of the mechanisms we can use for managing pain. That name is a mouthful, so I call these counter-irritants. (Read my post on birth combs as a DNIC tool here.) The principle is that if a laboring mom adds a pain or discomfort on her body during a contraction (like biting her lip, pressing her fingernails into her palm, or putting ice on her back), that helps to distract her brain from the pain. TENS, sterile water injections, acupressure, and birth combs are all DNIC tools for labor.

One theory for why these are effective is that the pain from these sensations causes a release of endorphins, endogenous opiates that help to reduce our perception of pain.

Another has to do with how the brain processes stimuli coming in on various pathways. (This is similar to the Gate Control mechanism of pain, which says that when we provide stimuli on fast-moving nerve pathways – like through sound, smell, touch with our sensitive fingers and toes – then those block some of the pain coming in on slower pathways – like labor pain.)

Chaillet, et al says that DNIC primarily reduce the intensity of pain. I believe that they can also help to reduce the unpleasantness of the pain. (see my post here for the difference between the intensity of pain and the unpleasantness of pain.) If mom is in control of the counter-irritant, it may give her more of a sense of control over the labor pain. She may feel like she can’t escape the labor pain (it’s highly “unpleasant”) but that she could stop biting her lip anytime she wants… being in control of something is better than feeling totally out of control. It’s one way of “working with labor pain.”

In childbirth classes, we can talk about counter-irritants by suggesting options to the pregnant parent (ice, squeezing something, TENS). We can use the concept to better explain sterile water injections (some parents are mis-educated in advance, and think that the injections themselves relieve pain… they’re shocked at how much the injections hurt! So, we want to explain in advance that they do hurt… like a bee sting… and that’s the idea, because they trigger an endorphin release.

In classes, we can also let the support person know that some people in labor develop a spontaneous ritual where they are causing pain to themselves (like pulling their hair)… help the partner understand that the person in labor is looking for counter-irritant – an uncomfortable sensation to distract her from the pain, and they can help her find one that gives that counter-stimulation but doesn’t harm her (like squeezing birth combs).

In the Bonapace method (I’ll post on that tomorrow), the DNIC mechanism that is taught is for the partner to do painful pressure on acupuncture trigger points. I personally prefer using only counter-irritant techniques that the person in labor applies and controls. I personally don’t like to teach partners to do anything painful to a woman, even if it might have benefit for labor pain. (A licensed massage therapist who has been clearly trained in safe high pressure massage I have no concerns about.) If I were to teach this in a class, I would set clear expectations that the laboring woman controls this firm massage – she asks for it to be done, and if she doesn’t like it, she tells her partner to stop, and her partner should stop.