Consider the Source: An Interview about Nitrous Oxide with Judith Rooks

Our Consider the Source series offers an inside look at research from the researchers themselves. In this installment, my guest is a prominent midwife-researcher who was the lead investigator on The National Birth Center Study published in the New England Journal of Medicine, researched and wrote the landmark book, Midwifery and Childbirth in America, and sits on the Editorial Board of the international journal of evidence-based maternity care, Birth, among many other distinctions. But she has not actually conducted any of the clinical trials on the topic at hand – nitrous oxide (also known as “gas and air”) for pain relief in labor.

Instead it was her experience overseeing arguably the most important systematic investigation of labor pain and its management that led Judith Rooks to begin advocating for greater access to nitrous oxide for laboring women. In this interview, Rooks discusses how she became so passionate about nitrous oxide, the American College of Nurse-Midwives’ new position statement on the topic, and why advocates for safe and healthy birth practices should join the movement to improve access to this important option for childbearing women.

Since many of my readers will be unfamiliar with nitrous oxide in labor, I offer this YouTube video of a woman using gas and air in the second stage of labor. If I could have edited out the editorializing by the TV producer, I would have! So please ignore her and have a look at the birth of baby Willow.

Science & Sensibility: You have been a very vocal advocate for increased access to nitrous oxide for laboring women. How did you get interested in nitrous oxide?

Judith Rooks: In 2001 the Maternity Center Association (MCA, since segued into Childbirth Connection) and the New York Academy of Medicine convened an invitational evidence-based symposium on the Nature and Management of Labor Pain. I directed this project on behalf of MCA and began by forming a multidisciplinary steering committee of experts. Penny Simkin was one of the first people I asked to serve on that committee. When she agreed, I asked her to help me develop an agenda for the seminar, and thus the topics to be addressed. Penny suggested that nitrous oxide (N2O) should be included, even though it was so little used and known in the US. She told me that it is widely used in many other countries and has advantages that are needed in this country. I had known almost nothing about it, but educated myself as best I could, after which I agreed with Penny.

At that time, as now, the University of California at San Francisco (UC/SF) and the University of Washington (UW) Hospital in Seattle were the only hospitals in the United States that were still offering N2O analgesia to women during labor. Dr. Mark Rosen, who had 30 years experience offering N2O analgesia to women during labor at UC/SF’s Moffitt Hospital in San Francisco, agreed to conduct a systematic review of the risks and benefits of N2O analgesia for labor and presented his findings during the symposium. Systematic reviews of all other labor analgesics used in the US were also conducted and presented at the symposium—one presentation each for parenteral administration of opioids, paracervical blocks, and nonpharmacologic methods, and three presentations on epidurals, two to deal with the extraordinary lack of consensus regarding the unintended effects of epidural analgesia on labor and its outcomes, and a third paper to describe side effects, necessary co-interventions, and the care required by women who labor with an epidural. Other systematic reviews were presented on the nature of labor pain, pain and women’s satisfaction with the experience of childbirth, and the degree to which American women have access to a choice of methods to relieve and/or help them cope with labor pain. Manuscripts of the systematic reviews were published in a special issue of the American Journal of Obstetrics and Gynecology.

I began to think more deeply about labor pain as a result of planning and directing this symposium, and I learned a lot from the experience: Epidurals can virtually eliminate labor pain but have strong negative effects on the normal physiology of labor, thereby causing a myriad of complications and other negative effects, including an increase in operative deliveries (forceps, vacuum extraction, or cesarean deliveries) and fewer spontaneous vaginal births. Opioids are not very effective at reducing pain and have negative effects on newborns. Paracervical blocks provide effective pain relief but are associated with adverse fetal and neonatal effects. Nitrous oxide is not a potent analgesia but is safe and seems to help most women who use it during labor. Nonpharmacologic measures help to relieve labor pain and have minimal or no side effects; but even women who want an entirely drug-free birth often need something more at some point during labor. Use of epidurals was increasing every year, as was the cesarean section rate and the even higher rate of total operative deliveries. I was and am still on the Editorial Board of Birth, a highly respected multidisciplinary international professional journal that focuses on pregnancy and birth. Reading and reviewing papers about childbirth in other countries made me increasingly aware that women in most English-speaking (or Scandinavian) countries have more options for pain relief during labor, whereas most women the US were increasingly being offered an epidural or nothing. I decided to try to “bend the curve” by expanding access to nitrous oxide.

Science & Sensibility: What do you see as the major benefits of nitrous oxide? Are there risks women should be aware of?

Judith Rooks: The major benefits are mainly lack of disadvantages associated with relying on epidurals, opioids and nonpharmacologic methods to relieve and help women cope with pain during labor:

After almost a century of use by many millions of women in countries with high standards of medical care and research, no studies or published observations have identified any negative effects of maternal use of nitrous oxide analgesia on the alertness and responsiveness of the newborn during the important early period of maternal-infant bonding or on early effective breastfeeding. The newborn of a woman who used nitrous oxide analgesia during labor is not at increased risk of respiratory depression. A pediatrician armed with a drug to counter the effects of opioids does not need to be present at the birth. Her newborn will not be admitted to a neonatal intensive care unit (NICU) for observation on the basis of risks associated with her method of labor analgesia.

Every analgesic and anesthetic drug that enters a woman’s body during labor passes through the placenta, enters the blood of her fetus, and remains active until it is detoxified or eliminated. Opioids (narcotics derived from opium and synthetic drugs that have the same effects) and the anesthetics used in epidurals are detoxified relatively slowly by the liver. Any opioids and anesthetics that are in the baby’s blood at birth have to be detoxified by the baby’s liver, which is immature and not very efficient. It can take several days for a newborn’s liver to eliminate them completely. Opioids depress respiratory function. Babies born with opioids in their blood may need to be resuscitated immediately after birth and tend to be sleepy and unable to nurse effectively. Anesthetics used in epidurals enter the mother’s blood in low amounts, but can still have effects on the newborn. N2O also passes through the placenta and enters the baby’s blood but is rapidly eliminated from the mother’s body (and thus the body of her fetus) through her lungs. Any nitrous oxide that is in the baby’s blood at birth is eliminated as the newborn takes its first few breaths of air. Opioids should not be used close to the time when the baby is expected to be born, yet many women need analgesia during a rapid delivery. Since nitrous oxide does not make the baby less responsive or depress respirations, it can be used up to and during the actual birth without increasing the risk of an unresponsive baby that needs to be resuscitated; it is never too close to the delivery for a woman to continue using nitrous oxide.

Nitrous oxide does not have any negative effects on the normal physiology of labor—the pulsatile release of endogenous oxytocin from the mother’s pituitary gland, maintenance of uterine muscle tone, the force and effectiveness of uterine contractions, blood flow to the uterus, the ability of the fetal head to rotate from a posterior position to an optimal position during second stage, and the mother’s ability to sense when and how to push most effectively, maintain upright positions, and change her posture as needed. There is no need to administer synthetic oxytocin (Pitocin) to make up for the lost effectiveness of endogenous oxytocin and no increased need to use forceps or force applied to the baby’s head by suction (vacuum) to rotate its head from a posterior position in order to deliver the baby vaginally. Because there are no negative effects on the normal physiology of labor, there is no reason to delay starting nitrous oxide during early labor out of concern that it will slow down or stop the woman’s labor before it can get a good start, and there is no reduction in the rate of spontaneous vaginal births.

In contrast, epidurals diminish the pulsatile release of endogenous oxytocin from the woman’s pituitary gland, which is in her brain. Pulses of natural oxytocin produced in the mother’s brain stimulate labor contractions. Reduction in the mother’s own supply of oxytocin causes labor to slow and become less effective. Most women who have epidurals are given an intravenous drip of synthetic Pitocin to make up for this loss. But a steady IV drip of synthetic Pitocin is very different from the synchronized release of natural (“endogenous”) oxytocin produced in and released from the mother’s brain. During normal labor there is a feedback loop between the release of oxytocin by the woman’s pituitary gland and the frequency and intensity of her contractions. Unfortunately, there is no way for an IV Pit drip to know how frequent, long or intense the mother’s contractions are. Without the feedback loop, it is easy to give a mother too much Pitocin, which can cause contractions that are too frequent, too long, and too intense. The arteries that bring blood to the baby through the placenta pass through the uterine muscle. When the contractions are too frequent, too long and too intense, the blood supply to the fetus can be severely compromised because the uterine muscle squeezes the arteries, not allowing enough blood to get through. Pitocin is the drug most commonly associated with preventable adverse effects of labor on babies. In 2007 Pitocin was added to the Institute for Safe Medication Practices short list of medications “bearing a heightened risk of harm,” which may “require special safeguards to reduce the risk of error.” Approximately half of all successful malpractice suits against obstetricians are related to misuse of Pitocin.

Nitrous oxide is not associated with any of the other known adverse effects of epidurals. These include :

  • a sudden drop in the mother’s blood pressure, in some cases leading to an emergency cesarean section
  • persistent fetal occiput posterior position in labor, highly associated with cesarean section for slow labor progress
  • need for bladder catheterization, which increases the risk of urinary tract infections
  • maternal fever in labor, which, despite not being infectious in origin, will often lead to neonatal sepsis work-ups and separation of mothers and babies after birth

Finally, a woman who is having an epidural requires continuous electronic fetal monitoring and an intravenous infusion as precautions against such complications. As a result, a woman who is having an epidural is tied to her bed by tubes and wires that connect her to the equipment that is providing the epidural, the intravenous infusion, and the equipment for continuous electronic fetal monitoring. None of these things are necessary for a woman who is using nitrous oxide, although her mobility is constrained by the need to access the source of the Nitronox (a blend of 50% nitrous oxide and 50% oxygen). But many women who use nitrous oxide don’t use it during their entire labor. Some women set it aside once their cervix has opened fully and they feel the urge to push. If the equipment for use of nitrous oxide is portable, a woman can continue to use it while walking, going to the bathroom, or relaxing in a tub of warm water. And it is not necessary for her to be attached to other equipment.

Although there are several relatively effective nonpharmacologic ways to help women cope with labor pain, most of them are not provided in most American hospitals. Some women who enter labor wanting to avoid an epidural come to a point, especially during their first birth, at which they feel that they cannot take the pain any longer and must have some kind of pharmacologic help. Although a pain crisis can occur at various points during labor, it is not unusual for a women to become exhausted and ask for an epidural during the period shortly before her cervix becomes completely dilated, when she would begin to feel the urge to push. Some women get a second wind once they move into the second stage of labor, but if she gets an epidural at that point, she will have it on board for the remainder of her birth. Although a woman who wanted to avoid an epidural should be able to change her mind and have one, she should also have access to a method of pain relief that is simple and fast to start, takes the edge off her pain and helps her cope, but can be put away—or continued, at her choice—once the crisis has passed, if she wants to re-engage and push with full sensation while giving birth.

Every woman and labor is unique. There is no single best method of labor analgesia. Every method has advantages and disadvantages, and different women value different things. Women should have choices, and some will do better and be more satisfied if they can use a variety of methods at different stages of their experience of giving birth.

Nitrous oxide can be started simply, quickly, easily and safely and begins to take effect almost immediately. There is no need to wait until an anesthesiologist or nurse-anesthetist is available to insert a catheter into the epidural space surrounding the woman’s spinal cord—a delicate procedure that requires sterile conditions. And, because nitrous oxide does not interfere with the normal forces of labor, it is not necessary to wait until labor is well established before the woman can begin to use it. Women who want to have an epidural can use nitrous oxide while they wait to be able to have an epidural.

After a brief period of explanation and supervision, nitrous oxide is self-administered through a mask that the woman holds to her own face. Self-administration allows the woman to determine when and how much nitrous oxide she uses. She can pick the mask up and use it as much or as little as she wants. She can also control the amount of nitrous oxide she takes in by adjusting the speed and depth of her inhalations. Being able to control her use of analgesia gives many women a reassuring sense of self-control.

Rapid elimination of N2O through the lungs means that if a woman decides after starting to use nitrous oxide that she doesn’t like it or no longer needs it, she can set the mask down and stop inhaling the gas. Her body will be completely free of nitrous oxide in less than 5 minutes. In contrast, it may take many hours for a woman’s body to be completely free of the effects of an opioid or epidural.

Science & Sensibility: How many hospitals or birth centers are using nitrous oxide in the United States?

Judith Rooks: To my knowledge only two hospitals in the United States are using as of early April 2010—the University of Washington (UW) Hospital in Seattle and the University of California at San Francisco’s Moffitt Hospital in San Francisco. The company that was manufacturing the equipment for self-administration of Nitronox (the 50%/50% blend of nitrous oxide and oxygen that’s used during labor) lost its subcontractor almost two years ago, resulting in a total lack of new equipment. As a result, hospitals and birth centers that wanted to start using it have not been able to move forward. Now another company is preparing to begin making new equipment. At least two hospitals and one birth centers are in line to buy the equipment and begin to use it as soon as it becomes available. Some other hospitals are considering it. I believe that there will be considerable early demand from smaller hospitals that cannot provide access to epidurals at night and during weekends.

Science & Sensibility: The ACNM Position Statement discusses two concerns with the use of nitrous oxide in labor: reproductive health risks for health care personnel who have repeated exposures to nitrous oxide in the workplace and a theoretical risk of injury to neurons in the newborn’s brain. These are cited as barriers to increased availability of nitrous oxide in the U.S. How have other countries addressed these concerns?

One long-standing concern relates to possible reproductive risk (more months to conceive, possibly due to early spontaneous abortions) among female health workers, including midwives and nurses who work closely with women using nitrous oxide analgesia during labor. This was a problem during an earlier time, especially in the United Kingdom (UK), where many hospitals were not well ventilated and people weren’t aware of the need to prevent the breath exhaled by women using nitrous oxide analgesia from entering the ambient air. Nitrous Oxide inhaled by a woman during labor stays in her body for only a short period of time before it is eliminated by her lungs. It is important for her exhaled breaths to be captured and pulled out of the room. Now that this is understood, a “scavenging” capacity has become an integral part of the equipment for using N2O. The woman breathes N2O and oxygen from a mask and exhales carbon dioxide and N2O back into the mask, which suctions it away. Eventually it is released into the outside air at a time and in a place and manner that are safe. Although nitrous oxide is a “greenhouse gas”, the amount used for medical and dental purposes is minor compared to other sources of nitrous oxide in the earth’s atmosphere, and it is not a poisonous gas that people should be afraid of in low concentrations. Nitrous oxide is produced when organic materials that contain nitrogen are burned or broken down in other ways. The leaves of deciduous trees contain a nitrogen that is turned into N2O by bacteria in the soil under a tree. Humans have always been exposed to low concentrations of naturally occurring nitrous oxide and have evolved an effective way to deal with having it enter their bodies.

The National Institute of Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA) are responsible for safe use of all anesthetic and analgesic gases in the United States. Their recommendations for maximum occupational exposure to N2O are more stringent than the rules that govern use of N2O in many other countries. Current OSHA recommendations call for limiting occupational exposure to N2O to not more than an 8-hour time-weighted average concentration of 25 parts per million (ppm). Although the Netherlands adheres to the same standard, the UK, Italy, Sweden, Norway and Denmark set 100 ppm as their upper limit. NIOSH’s recommendation to limit occupational exposure to nitrous oxide to 25 ppm was established during the 1970s, without benefit of actual data. Nevertheless, the American Society of Anesthesiologists (ASA), NIOSH and OSHA all agree that this standard has been effective in protecting American health workers.

The concern about a theoretical risk of injury to neurons in the brain of a human fetus while its mother uses N2O analgesia during labor resulted from research that found seemingly severe but reversible nerve cell damage in the brains of baby rodents, mainly rats, exposed to very high concentrations of N2O, as well as alcohol and many other neuro-active drugs, including all general anesthetics. The period of susceptibility in rodents coincides with the time during which the immature brain is growing and developing at a rapid rate—the first week of life for a baby rodent. The comparable period for humans is from the 6th month of gestation until about three years of age. The research leading to this concern began with research on the pathology that underlies fetal alcohol syndrome and expanded to looking at whether other drugs might causes similar damage to the brains of baby rats. A large body of laboratory research was done and published in the 1990s but did not gain widespread attention until about 2007, which also happened to be the time when midwives and others were becoming concerned about the lack of access to labor analgesia choices for women in the US, resulted in growing interest in nitrous oxide. By 2008 two US hospitals were considering beginning to offer nitrous oxide analgesia to women during labor—a major academic medical center in the southeast and a Kaiser Permanente hospital in California. Both hospitals were leaning towards going forward with N2O obstetric analgesia when leaders of their anesthesiology departments attended a national professional meeting during which this body of research was summarized and discussed. Shortly thereafter the anesthesiology departments of both hospitals decided against any expanded use of nitrous oxide, decisions that were probably minor from their perspective. The much bigger concerns among the anesthesiologists who learned about the damage to rat brains from exposure to nitrous oxide related to the important role of N2O as a component of anesthesia for long but essential surgeries on infants and toddlers.

Nitrous oxide has long been a staple of anesthesia for surgery, not as a single agent but as part of a mixture of anesthetic gases. The addition of nitrous oxide makes it easier to both induce and bring a patient out of anesthesia with less stress, including preventing unpleasant and sometimes very frightening memories. Those benefits are considered so important for children that concerns about risks associated with exposing children to nitrous oxide created a crisis for anesthesiologists and pediatricians, who continued to use nitrous oxide during pediatric surgeries until more information on the clinical significance of the baby-rat studies for humans could be assessed. This all occurred in the context of a wider challenge to continued used of nitrous oxide in anesthesia practice in the US. Development of new anesthetics that can be administered intravenously has made it possible to give adult patients pure oxygen to breathe during surgery. Several studies have shown that patients who breathe 100% oxygen during surgery have fewer infections and better wound healing, apparently due to higher levels of oxygen in their body tissues. A randomized trial that proved this was published in Anesthesiology (the journal of the American Society of Anesthesiologists) in 2007 under the title “Avoidance of Nitrous Oxide for Patients Undergoing Major Surgery.” The study was conducted as part of the Evaluation of Nitrous oxide In a Gas Mixture for Anaesthesia (ENIGMA). An editorial published in the same issue of Anesthesiology pointed out that the important finding of the study was the benefit of high inspired oxygen rather than avoidance of nitrous oxide, which, she pointed out, “is certainly useful for inhalation inductions in children, as well as for analgesia in laboring parturients [women giving birth] or in patients having dental procedures.”

In October 2008 Anesthesiology published a comprehensive review of the biologic effects of nitrous oxide authored by an international team of leading anesthesiologists from the UK and Germany. They noted that, although N2O causes morphologic neurotoxicity in the immature brains of baby rats, this “occurs at doses in excess of those normally administered in clinical practice (i.e., in hyperbaric conditions) and resolves within 3 hours.” They further found no evidence of neuropathology in neonatal rat brains from exposure to N2O concentrations less than 75%. The abstract summarized the situation:

Nitrous oxide is the longest serving member of the anesthesiologist’s pharmacologic armamentarium but remains a source of controversy because of fears over its adverse effects. Recently, the (ENIGMA) trial reported that that nitrous oxide use increases postoperative complications; further preclinical reports have suggested that nitrous oxide may contribute to neurocognitive dysfunction in the young and elderly. Therefore, nitrous oxide’s longevity in anesthetic practice is under threat. In this article, the authors discuss the evidence for the putative toxicity of nitrous oxide, from either patient or occupational exposure, within the context of the mechanism of nitrous oxide’s action. Although it would seem prudent to avoid nitrous oxide in certain vulnerable populations, current evidence in support of a more widespread prescription from clinical practice is unconvincing.

Blood levels of nitrous oxide in women during labor never go very high. Self-administration protects the mother and fetus from getting too much N2O. If the mother becomes drowsy, her hand will fall away from her face, the supply of nitrous oxide will turn off, and she will begin to breathe room air. Nitrous oxide as used during labor is not a very potent analgesia—enough to take the edge off the pain but not a concentration that is even close to what was being given to the poor baby lab rats used in the studies that caused so much concern.

Science & Sensibility: Do you think there are other barriers to increasing access to nitrous oxide: perhaps economic, logistical, or cultural?

Judith Rooks: Lack of equipment has been a big problem during the past two years because the demand for nitrous oxide analgesia was not great enough for the company that had produced the equipment for many years to find a new subcontractor to make the equipment when the one that had been doing so stopped. It turned out to be the problem of all “orphan drugs”, for which there is not enough demand for large companies to invest in producing a supply to meet a limited demand. Now a new company is preparing to begin making new equipment, but it has been a big problem.

Epidurals are big money makers for hospitals and, of course, for anesthesiologists, whereas nitrous oxide is an old, off-patent, cheap drug that can’t compete as a money maker (but may at some point compete as a money saver, as the US moves towards placing value on cost-effective health care). Profit is a powerful force in American health care. If no one is making a profit, no one is pushing for a product to have a place on the shelf, whereas those who are making big profits are always trying to push the product that is not profitable off the shelf.

Once anesthesiologists decided to introduce epidurals for labor analgesia it became important to get rid of anything that might compete. If a hospital or physician wants to be able to tell pregnant women that they can have an epidural during labor, the hospital has to make a commitment to providing access to an epidural 24 hours a day every day of the year. It requires more than 5 full-time people to provide any service 24/7, and it costs a lot to pay full-time salaries for 5.2 anesthesiologists and/or nurse anesthetists. In order to make it practical for a hospital to providing labor epidurals on a 24/7 basis, it is necessary for a large proportion of women who give birth at that hospital to have epidurals. Nitrous oxide was maligned as old fashioned, dangerous to the health of nurses and midwives, making women vomit and thereby posing a threat to their lives because they might inhale some of their vomit, etc. Bad-mouthing nitrous oxide is still going on very actively, whether by ignorance of changed facts (e.g., much lower doses than were used decades ago, scavenging to prevent contamination of the air), repetition of unfounded rumors, financial considerations, or a desire to avoid the need to provide the time-intensive care needed by women who are experiencing some degree of pain.

Most obstetricians were delighted to hand responsibility for dealing with labor pain to anesthesiologists. Some time ago I had protracted communication with a fine obstetrician who banned continued use of nitrous oxide analgesia in an major university hospital when he went there to head the department of obstetrics and gynecology during the 1990s. After he offered several unconvincing rationales for having banned it, he said that he is just uncomfortable seeing women in pain. An epidural is the only method that can totally obliterate labor pain for an individual woman and result in a completely quiet labor unit, with no woman making any sound associated with discomfort. Many obstetricians may resist any change that would put them in the position of having to deal with more women who are experiencing some level of pain.

Most young nurses (all but a few OB nurses at this point) have had little if any experience with women who are laboring without an epidural and have never been taught or had role models to help them learn how to comfort and support a woman who does not have an epidural. Continuing education for labor-unit nurses tends to focus on the technical aspects of care, such as electronic fetal monitoring. Little value is assigned to being able to work effectively with a woman who is trying to go through labor and give birth without an epidural. The few nurses who are interested and able to do it may be criticized by their peers for “spoiling” the patients. Doulas would be a good solution but are not widely accepted in obstetrics. In addition, doulas are most effective as agents of the pregnant woman, but most women can’t afford to hire on and it is not clear that doulas employed by a hospital would be as effective.

Epidurals are clearly the most effective way to eliminate pain during labor. That makes them “the Gold Standard”, even though complete obliteration of pain is not the real goal for many women during labor. Superficially it may seem silly, stupid or sadistic to advocate for introduction of a “less effective” method of analgesia for women during labor. And women are most likely to want to use the method that is “best”.

Few women have full information about the pros and cons of various approaches to reducing and helping women cope with labor pain. The benefits and harms are complicated, time during prenatal visits is limited, and childbirth education is now being provided mainly by hospitals which slant it to encourage women accept and want the kind of care that the hospital can provide most expeditiously.

American health care is remarkably isolated from what is happening in other countries. Although the recent focus on the need for “health care reform” has informed many Americans that health status of Americans is poorer overall than that of the citizenry of many wealthy countries, most Americans think that the only thing wrong with American health care is that some people can’t afford it. There is little understanding that overuse of invasive procedures can actually result in harm, and that more, more expensive, and more “sophisticated” care is not always better. In addition, it is hard for Americans to learn anything about health care from another country. Many American physicians don’t read other English-language medical journals and discount research conducted in other countries as not being as good, important or valid as studies done in the US. As a result, we rarely benefit from progress that is being made in other countries. Most of the use of nitrous oxide analgesia occurs in other countries, so most of the research on it comes from other countries too. Most American physicians don’t have any idea that two of our best academic medical centers, UC/SF and the University of Washington, provide nitrous oxide anaglesia to women during labor.

Nitrous oxide analgesia is most compatible with the midwifery model of intrapartum care, and the supply of midwives is very limited in the United States.

The Joint Commission on Accreditation of Hospitals (JCHA) mandates regular pain assessments of all hospitalized patients, mainly by asking patients to rate the degree of pain they are experiencing using a standard 0 to 10 Numeric Rating Scale. Asking women who are trying to cope with labor pain to rate the degree of pain they are experiencing at regular intervals is counterproductive, since women who don’t want or can’t have an epidural are focusing on something else; it isn’t helpful to interrupt their focus by asking them to think about pain. Some tools that replace use of the Pain Assessment Rating Scale with a way for nurses and midwives to assess how the woman is coping with labor have been developed. I believe that Penny Simkin has developed such a tool, and one was described in a recent issue of the Journal of Midwifery & Women’s Health. This approach is acceptable to the JCHA but is not widely known or used.

Science & Sensibility: If consumers or health care providers are interested in reintroducing nitrous oxide in their communities, what steps should they take?

Judith Rooks: Pregnant or hope-to-become-pregnant women should talk to others, especially maternity care providers in their areas, about the need for nitrous oxide as an option for women who will give birth in local hospitals. Talk about it. Ask about it. Request it. Find out who is responsible for the hospital at which you will or would use for a birth- some kind of board of directors is responsible. Get their names and addresses, and send them letters asking for this. Do the same for the leaders of the departments of obstetrics and anesthesiology. Invite someone who can speak about this to give a talk somewhere in your city or town and get other women (and their partners) involved. Ignorance is the enemy, and in this case it is not just ignorance. Many professionals who think they are well informed about options for analgesia during labor are ignorant about options to epidurals but don’t know—and would be insulted by any inference—that they are ignorant. Don’t antagonize people and make enemies, but provide opportunities for them to learn more. Go on talk radio programs. Local public affiliates of National Public Radio (NPR) are usually open to discussions of topics of interest. Inform yourself thoroughly first. Reading and having a copy of the ACNM Position Statement on Nitrous Oxide for Labor Analgesia is a good place to start. This blog post is also full of authoritative information.

To arm yourself fully with the most current information, you should consider joining the nitrousoxideduringlabor listserv. Go to (http://health.groups.yahoo.com/group/N2Oduringlabor/) and follow directions to join. After you join, return to the listserv home page and click on “Files” in the light blue sidebar on the left side of the page to go the Files section, which contains copies of important published papers and other documents relevant to use of N2O analgesia during labor. As a member of the listserv you have access to all of those documents, as well as most of the messages that have been sent to members of the listserv. The files are listed alphabetically based on the name the given to the gave to the file when it was posted on the website. For example, an important paper by Sanders et al. is listed alphabetically after a very important systematic review of the best available evidence about the safety, risks and use of nitrous oxide for labor analgesia authored by Dr. Mark Rosen, Chief of Obstetric Anesthesia at the University of California at San Francisco and published in the American Journal of Obstetrics and Gynecology in 2002. Both are key documents. Mickey Gillmor, who is on the faculty of the largest midwifery education program in the US (the Frontier School of Midwifery and Family Nursing) helps me run the N2Oduringlabor website.If you have any trouble making this work for you, please let Mickey or me know. My email address is jprooks1@comcast.net. Mickey’s email address is mickey.gillmor@gmail.com.

This advice basically applies to health care workers too.

I think that N2O analgesia is going to become increasingly in demand as the growing imbalance between the supply of anesthesiologists and nurse-anesthetists to provide 24/7 access to OB epidurals and the need for some kind of relatively effective analgesia for women during labor. I believe that women are currently being urged to accept being induced (which leads to more cesareans) or have an elective preemptive cesarean in order to avoid the possibility of going into labor over the weekend or at night with no choice but a hospital that does not have weekend or night coverage for epidurals. I assume that is part, maybe even a significant part of the reason for the great and growing disparity in the average number of births that occur on specific days of the week in the US. As this problem becomes more apparent—amid increasing evidence of increased harms to both mothers and babies of unnecessary inductions and cesareans—the animosity among many anesthesiologists and some obstetricians towards any method of labor analgesia other than the “gold standard” epidural will have to wane.

Information about nitrous oxide is slowing seeping out to women, not all of whom want an epidural; that is why I am doing this interview—as long and tedious as it may seem. Our Bodies Ourselves, Childbirth Connection, and a growing number of books, movies, journals and blogs are bringing more and more women better, fuller and more evidence-based information about their choices and chances to have a non-surgical physiologic birth.

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  1. | #1

    FEW! I got through all that. I have to say I wished I had been given another option besides the epidural. It ruined my labor both times, and I had to shut that thing off to get my VBAC. I never wanted it – I was afraid of it, and I had bad reactions – but it was my only “option.”

    I do remember this being talked about at NIH and someone bringing up the fact that the hospital staff’s exposure to was considered dangerous. It’s interesting to hear that the exposure concerns are probably not well founded.

    I have to say though, I’m still going for a 100% natural delivery next time. After going through what I did the last two times, I think feeling everything will help me birth better. I could be delusional, but many women before me have done it!

  2. avatar
    | #2

    The UK Channel 4 documentary series has freely-available videos on the series website, many of which show women using N2O AKA “gas and air” or Entonox e.g.: http://lifebegins.channel4.com/birth/the-process/pain-control/gas-and-air-entonox/becky-needs-gas-and-air/
    One study found that it was used in most hospital births and half of home births in the UK: cited here, with links to birth stories where it was used,if anyone is interested http://www.homebirth.org.uk/pain.htm

  3. avatar
    | #3

    That is really interesting!

  4. | #4

    Thank you for this interview! I’ve often wondered why my Canadian friends had this as an option, and knew it was more popular among midwives than OBs there, but I never understood why that was true, and why we don’t have it as an option in the States!

    I would like to hear more about women’s satisfaction with use of N2O – my friends reported that it didn’t help much and just made them feel nauseated – but they were still happy they had a low-risk option to try when they were feeling overwhelmed.

  5. | #5

    As a nurse midwife who recently joined a university based practice where there is a real demand for unmedicated birth, I found this very interesting and enlightening. I came from a practice where there was less interest in “natural” childbirth. In this practice patients often have doulas with them during their labors and there are even volunteer doulas who can be called upon for patients who come to the hospital in labor without one but with a desire for NCB. The labor and delivery nurses self select to work with the NCB patients and I have been so fortunate to work with great supportive nurses and doulas since I have been here.
    Thanks for the great information and for the support for another option for women during childbirth.

  6. | #6

    I read the whole thing, too! This was a great, very informative article, not just about nitrous oxide (about which I knew nothing) but also for providing an easy-to-understand overview of the current state of hospital-based OB care. I have bookmarked and will share as much as possible.

  7. avatar
    canoe chick
    | #7

    sufficiency :
    Thank you for this interview! I’ve often wondered why my Canadian friends had this as an option, and knew it was more popular among midwives than OBs there, but I never understood why that was true, and why we don’t have it as an option in the States!
    I would like to hear more about women’s satisfaction with use of N2O – my friends reported that it didn’t help much and just made them feel nauseated – but they were still happy they had a low-risk option to try when they were feeling overwhelmed.

    We use it all the time up here in Canada! From my own experience with hundreds of women (primips), I think about 1/3 of women who try it love it – they say it doesn’t take away the pain, it just means they don’t care about it. The other 2/3 who try it don’t like – many because it does make them feel nauseous, others don’t like it because they found the mask confining or bothersome. (I would love to see us get the small nasal cannulas like they have in UK hospitals and birth centers – we just have big masks). It really is a great option for some women – and options are always good!!!

  8. | #8

    I did use NO2 during transition with the birth of my last child (2 months ago)- in Canada. I found the method of delivery to be very troubling
    1- because the mechanism to receive the gas is through inhalation, and the amount received is dependant on the deepness of the breaths, it was difficult to get the amount needed for it to “work”- because my contractions were on top of each other and long I was not breathing very deeply- which meant that I was not able to get the full effect of the gas.
    2- because the gas is given through a mask I found it awkward to deal with and worse, became claustrophobic with it in my face.
    But regardless, I knwo that it is a very good option for most women- but would like to see the method/mechanism for delivery changed to be easier for the mother in labour.

  9. avatar
    | #9

    I used NO2 when birthing my first child, in the UK (midwife in hospital) mainly because the epidural failed after 20 mins (I didn’t know any better and I was hooked up to Pitocin!). I LOVED IT! Like someone has said, it didn’t really take the pain away, I just didn’t care. It was kind of like being rather drunk but without the “oh dear, I’m going to throw up / fall asleep” feeling. It’s known as Laughing Gas for a reason – my hubbie had to take the facemask away from me and give it back when the contractions came. I do vaguely remember smiling at him saying “Weeee, away with the fairies!”. This same son has already had used it too when he was 5 years old for a cavity filling as it was highly recommended by the pediatric dentist for “destressing” that situation for a small child.
    Wish they had it here in the US… its just enough to take the edge off especially at the end / transition / sowing up any tears.

  10. avatar
    Wendy Muir
    | #10

    I am one of the Canadians who are accustomed to the use of NO2. As a maternity nurse in the past, my patients used it a fair amount in transition. During one of my own labours, number four of five, NO2 was suggested when the nurses saw some non-reasuring tracings, so I tried it. I QUITE liked it, I was definitely giggly. Although I knew the contractions were still happening and painful, it was almost as if I was separated from them, like someone else was having them. Unfortunately my son’s heart rate tanked so they took away the NO2 and put on just O2. It was hard to deal with the contractions then. Thankfully I arrived in the OR fully so they let me push him out rather than do the section. Although I liked the NO2, I didn’t use it for the birth of my fifth babe. Didn’t need it. Tried Demerol when it was offered with my first babe, hated it, never went near it again. Presently, as a Lamaze certified Childbirth educator and DONA doula, I see it mostly with the mask off, using just the round connector to breath on.

  11. avatar
    Wendy Muir
    | #11

    I am one of the Canadians who are accustomed to the use of NO2. As a maternity nurse in the past, my patients used it a fair amount in transition. During one of my own labours, number four of five, NO2 was suggested when the nurses saw some non-reasuring fetal heart tracings, so I tried it. I QUITE liked it; I was definitely giggly. Although I knew the contractions were still happening and painful, it was almost as if I was separated from them, like someone else was having them. Unfortunately my son’s heart rate tanked so they took away the NO2 and put on just O2. It was hard to deal with the contractions then. Thankfully I arrived in the OR fully, so they let me push him out, rather than do the section. Although I liked the NO2, I didn’t use it for the birth of my fifth babe. Didn’t need it. Tried Demerol when it was offered with my first babe, hated it, never went near it again. Presently, as a Lamaze Certified Childbirth educator and DONA doula, I see it mostly with the mask off, using just the round connector to breath on.

  12. | #12

    Am I know the umpteenth person to forward you this npr story?


  13. | #13

    I heard it first from you, Karen! But then logged into Facebook and saw it shared in a few places. Thanks!!

  14. | #14

    Quite a complete post. Thanks for that Amy.

    I have not seen NO2 used in any hospital I have worked in, outside of the operating rooms of course.

    >> they say it doesn’t take away the pain, it just means they don’t care about it.

    N02 definitely does block pain. I remember demos in medical school where a student was exposed to a noxious stimuli (painful) without the N02 and then with N02. It definitely took a more painful stimuli before the N02 breathing student started to register it as pain (all with consent of the student of course.) Anethesiologists actually use N02 additively with other anesthetics to be able to reduce the amount of anesthetics that are needed. Anethesia is measured in MAC, which is the amount of anesthesia that will make 50% of people not move to a painful stimuli. N02 at 100% is only 1/2 MAC, so it clearly won’t make one completely numb – but it does have an effect.

    It also causes euphoria and a general sense of well being / happiness, hence the name Laughing Gas.

    I have to say, though, that I am fascinated/surprised that natural birthing folks would be proponents of this. The whole idea (I thought) of natural birthing was to somehow experience labor as it is. Breathing a substance that causes a euphoria greater than any illegal drug hardly seems to be along that vein. Breathing high concentration NO2 can make one extremely high.

    I also find it fascinating that people would use an unsealed mask to deliver NO2. Dentists use a nosepiece that seals against the face that keeps the N02 from getting back out in the air (assuming the patient breaths in and out through the nose). Using a regular facemask to deliver it would certainly expose those around the patient to some of the N02. This of course would make their job more fun.

    The studies quoted on epidurals are all pretty biased against epidurals. As none of them are randomized, there is a tendency to cluster patients with protracted labors, which are likely more painful, into the group that got epidurals. This biases the study to show an association between epidurals and lower rates of vaginal delivery. The only fix would be a randomized study, which won’t ever be done as patients either want an epidural or they don’t, and they wouldn’t want to be randomly assigned to either group.

    As such, those that believe that epidurals are harmful will use the studies against the practice, and those that are OK with epidurals will go with their experience that people seem to do fine with them.

  15. | #15

    Wendy >> I QUITE liked it,

    Of course you did – at high doses it is a near orgasmic experience.

    So here’s one to ponder.

    We freak out at the idea of high school and college kids huffing various gasses for the high, yet we support the idea of using N02 for analgesia. Its really no different. In fact lots of those kids are huffing N02 bought from the grocery store, meant to make whipped cream with. So is this more dangerous than we let on, or are we scaring the kids away from something that isn’t actually that dangerous?

    One of the issues with the huffing is that pure N02 has no oxygen in it, so somebody can potentially asphxiate themselves breathing enough pure N02, and be happy while doing it.

  16. avatar
    Judith Rooks
    | #16


    I’m not very used to blogging so not sure whether this will go or not. I agree with the Feminist Breeder. I labored without any drugs and think that’s a great way to go, but there needs to be a middle road for women who don’t want or need an epidural but may need some kind of pharmacologic help at some point during labor. It is fine for you to be a purist, but there should be a middle road. What we have now is basically an epidural or nothing in many American hospitals, or an epidural or strong opioids. I want to give women more choices. You are speaking for yourself; I am trying to do something that will give more women a realistic hope of avoiding an epidural if that is what they want to do.

    Best regards and thanks for your comment.

    Judith Rooks

  17. avatar
    Judith Rooks
    | #17

    Dear QoB,

    Thanks. I hadn’t known about the UK documentary. I appreciate your message.

    Judith Rooks

  18. avatar
    Judith Rooks
    | #18

    Dear Sufficiency,

    I think that it is adequate for at least one-third of the women who try it, but it depends on who tries it. If women are offered the choice of an epidural, opioids, nitrous oxide, good midwifery care with constant support throughout labor, warm baths, a birthing ball, a wide variety of nonphamacologic methods, many will choose epidurals and be happy with their choice, many may try several different methods at different points during their labor and be satisfied, some will only use nonpharmacologic methods and be satisfied. The more methods that a woman has access to, the more likely she is to be satisfied. Nitrous oxide is the only pharmacologic method that a woman can begin to use and stop if she doesn’t like it (or no longer needs it). It will be completely gone from her body in less than 5 minutes. If she begins with an epidural and doesn’t like it, she can be rid of it in about 5 hours. If she receives opioids and then changes her mind, she and her baby can be completely free of any opioids in their systems within a few days, depending on the kind of opioid, how it was administered and the dose. Some women don’t like N2O at first but do like it after they learn how to use it. Lots of women really like it. I think that a lot of American women would be glad to have the choice.

    Thanks for your good question!


  19. avatar
    Judith Rooks
    | #19

    @Dani Arnold
    Dear canoe chick,

    Thanks very much for your comment—and question. I am going to pursue your question about use of smaller nose-only canulas with the anesthesiologist and midwife who manage use of N2O analgesia at UCSF in San Francisco and also with the president of the company that is in the process of beginning to produce new equipment for use of N2O analgesia by women during labor here in the US. If the scavenging function would not be negatively affected, I cannot see any reason why a smaller mask couldn’t be produced and offered. Or a mouth tube. A great question. If I find out the answer, I will try to provide it on this blog.



  20. | #20

    The interview was really eye opening – thanks for sharing this important information so that those of us who work in this field can begin to advocate for N2O as another option for birthing women in this country. I have long wondered why women that I knew went to other countries and used this method of pain relief – I thought that it was somehow outdated and that we were so much more sophisticated here in the US – this certainly opened my eyes, I think that N2O will be an increasingly popular option in the future. Thanks again for informing us all!!

  21. avatar
    Judith Rooks
    | #21


    Judith Rooks :
    I’m not very used to blogging so not sure whether this will go or not. I agree with the Feminist Breeder. I labored without any drugs and think that’s a great way to go, but there needs to be a middle road for women who don’t want or need an epidural but may need some kind of pharmacologic help at some point during labor. It is fine for you to be a purist, but there should be a middle road. What we have now is basically an epidural or nothing in many American hospitals, or an epidural or strong opioids. I want to give women more choices. You are speaking for yourself; I am trying to do something that will give more women a realistic hope of avoiding an epidural if that is what they want to do.
    Best regards and thanks for your comment.
    Judith Rooks

    @Nicholas Fogelson
    Hi Nicholas Fogelson,

    Thanks with your interesting story of an informal study of the effectiveness of N2O when you were in medical school.

    I understand your confusion about a blog related to normal birthing carrying a contribution that encourages greater use of a pharmacologic method of helping women cope with pain during labor. I applaud any woman who can go through labor without any use of any kind of pharmacologic help. I would love to see more women do that. But some women really, really need pain medication. The experience of labor pain varies so greatly between women and even from one birth to another for the same woman. Some women have excruciating pain that overwhelms them and can even cause them to experience something akin to a post traumatic stress disorder, to the extent, sometimes, of not wanting to every have another baby. Those who take care of women during labor should make it possible for the whole spectrum of women to have safe births that are not so painful that the woman cannot cope with the pain. At the same time, it is important not to let the method of pain management interfere with the progress of labor. There are no simple answers and no perfect method that is best for every woman. There is a need for epidurals. And there is a need for midwives and doulas and tubs in birthing suites, and the use of many nonpharmacologic methods to help women cope with labor pain without use of drugs. There is also an enormous need for American women to have access to a method of labor analgesia that is used by millions of women in other countries and has been nearly eliminated from use in the US. That is going to change. I hope you will support and help me and many others work towards adding nitrous oxide as an option for women giving birth in our hospitals.
    The mask by which N2O and O2 are delivered to a woman during labor is not unsealed. It is built so that her inhalation creates suction, which creates a seal while the woman is inhaling. As soon as she stops inhaling, the supply of N2O and oxygen snaps closed, but the suction (scavenging) function continues. She breathes back into the mask, which at that point us near her face but without a seal. The continuous negative pressure captures her exhalation. When she is ready to inhale again, she holds the mask against her face and the negative pressure created by her inhalation recreates the seal. The midwives and nurses who take care of a women who is using nitrous oxide during labor—and the patient herself—know that it is important to prevent N2O from escaping into the ambient air. Whenever there is no seal, no N2O comes out of the mask; the negative pressure (suction) continues, but the supply of N2O is cut off immediately.

    I am not against epidurals. Some women really need an epidural, and many other women really want one. I am concerned that there are not enough anesthesiologists and nurse-anesthetists to provide 24/7 access to epidurals in all hospitals, and that this shortage will get worse. However, there is a much greater shortage of other options for women who either can’t use an epidural, can’t access an epidural, or don’t want an epidural. That is why I am encouraging wider access to nitrous oxide.

    Judith Rooks

  22. avatar
    | #22

    I’m from the UK and have used just gas and air with all 4 of my children and loved it! I hated the idea of being completely helpless and losing sensation in my lower body from a epidural, I also disliked the reported effects of pethidine on both mother and baby so gas and air was a great compromise.

    The good thing about gas and air are that it definitely takes the edge off the pain,you can control it and if you have too much just resting up will clear your head again. Oh and the mouth piece is great for biting down on 😉 In the video link in the article the woman giving birth is using one of the mouth tubes rather than a full face mask and it is much much more pleasant than one of your Canadian commenter’s experienced.

    Just as a note, gas and air definitely does provide pain relief not just a sense of fuzziness as I ran out of gas and air (home birth) and I really noticed the difference. Fortunately re-supplies arrived quickly by taxi so I was straight back onto it asap. Interestingly the midwives mostly encouraged it once labour was really well established and contractions reaching the unbearable point so that you really felt the benefit of it. Before reaching for gas and air they used massage, a TENS machine, warm baths, birth ball and it my last labour a birth pool before starting on the gas and air which meant I really appreciated it and I suspect it was more effective like that.

    Secondly the midwives encouraged only light use during the second stage so that you could concentrate on pushing and weren’t too woozy.

    I personally find it astounding that it isn’t more widely available in the States as its a great half way house between fully medicated and completely natural. It also is the only drug that the woman herself has control over administration and dose…maybe that’s why I prefer it :)

  23. avatar
    | #23

    I found gas and air very helpful during my lovely home birth, but I think I would have hated a mask. I had a mouthpiece that I held between my lips/teeth – not claustrophobic at all.

  24. avatar
    Gail, Midwife in UK
    | #24

    Haven’t read the whole thing yet but just want to say that the Trust where I work uses disposable plastic mouthpieces, not masks. Very easy to use, nonconfining, and provides something to bite on for those women who like that. My personal belief is that it’s the anaesthesiologists who kept it from women in the USA so long, as it would probably greatly reduce the epidural rate! I was so surprised to discover it had existed for so long in the UK when I first read something about it a few years ago while an L&D nurse in the States. Long overdue there.

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