Nitrous Oxide Analgesia for Child Birth

by Claudia Copeland, PhD

laboring women using nitrous oxideAs a mother who has given birth naturally (no drugs or major interventions), I know firsthand how difficult the natural birth process can be. Though non-invasive techniques like hypnobirthing and acupressure worked wonders to ease the pain of my labor, it was still the most intense pain I have ever experienced.

Many of my friends ardently wanted a natural birth, but then caved in when the pain became too extreme. I have often thought that what so many women could use is a "middle path;" a mild analgesic that could be safely used during birth, with little or no effects on the baby. It would be okay if this analgesic let in some pain. For me, and for many women attempting natural birth, it would make all the difference to have just "a little something to take the edge off."

Nitrous Oxide -- That Little Something

As it so happens, that "little something" is available to women in almost every developed country -- except the United States. The drug is nitrous oxide, or laughing gas. It is mild, has little or no effects on the baby being born, and is used by midwives throughout the world for labor. It is not a strong anaesthetic, but it is effective for many women.

Dr. Mark Rosen, M.D., of UCSF Moffitt Hospital in San Francisco, describes it this way, "Although the efficacy of nitrous oxide has not been well defined and seems limited compared with that of epidural analgesia, it appears to provide analgesia at a level comparable to that of paracervical block and probably better than that provided by opioids. When applied properly, it appears that nitrous oxide inhalation can provide significant pain relief for at least 50% of patients, a conclusion reached 30 years ago."

In the U.S., however, it is currently available only in San Francisco (UCSF Moffitt Hospital) and Seattle (University of Washington Hospital), with approval for future use in one small community hospital in Hawaii (North Hawaii Community Hospital). For the overwhelming majority of women giving birth in the United States, nitrous oxide is not available as a choice.

Affect on Baby

Babies born under nitrous oxide analgesia are not significantly affected by it; Apgar scores, neonatal survival, and neurobehavioral assessments (Neurologic and Adaptive Capacity Score and Early Neonatal and Behavioral Scale) are not significantly different from those for unmedicated birth. It is excreted through the lungs, so in less than a minute, it is eliminated from the baby's body. In contrast, the opiates and cocaine-derivatives used in epidurals are processed through the liver. A newborn baby's immature liver can take months to eliminate the drugs.

Reasons Mothers Choose Nitrous Oxide

Doesn't lead to further intervention: Mothers like nitrous oxide because, in contrast to the epidural, it does not lead to the "chain of interventions" that often ends in cesarean section, which has become the birth method for almost one in every three American mothers.

Nitrous oxide also has no significant effects on the natural progress of labor. When used under standard conditions, side effects are minimal (such as dizziness or euphoria), and there is no significant difference in maternal oxygen saturation compared with completely unmedicated births and births with an epidural.

Self administered: Standard conditions for use of nitrous oxide during labor include a 50% oxygen mixture, scavenging equipment and a one-way valve to minimize escaping gas, and a hand-held mask, so that, if a woman were able to ingest a dose high enough to make her very dizzy or faint, her hand would fall from her mouth and the flow of gas would stop.

Helpful during rapid labor: Judith Rooks, a midwife and advocate for the use of nitrous oxide, states that "it is particularly helpful for women experiencing rapid labor, transition, second-stage labor, and while suturing the perineum. It can be extremely helpful for women who want to avoid an epidural, useful for women who have to wait for an epidural, and a blessing for everyone when there is a sudden, unexpected need for analgesia for an invasive procedure required because of an obstetric emergency."

Why Is Nitrous Oxide Not Widely Available to American Laboring Women?

Occupational Exposure: One legitimate concern is the occupational exposure of midwives and other workers to nitrous oxide. Midwives exposed to nitrous oxide (continuously, over 7.5 to 11 hour shifts) in older, unventilated hospitals in the U.K. had chronic exposures in excess of U.S. OSHA limits.(U.S. OSHA guidelines are more stringent than those of most other countries.) This could lead to reduced fertility in female workers.

However, midwives in newer hospitals with modern ventilation were found to have levels well below U.S. OSHA limits, even when the hospitals did not use scavenging equipment. Other studies of hospitals/birth centers/dental clinics have shown low levels of exposure when scavenging equipment is used. According to Dr. Rosen, the key is to use scavenging equipment; even if nitrous oxide is relatively safe, why not just get rid of it, so workers do not have to worry about occupational exposure? Scavenging equipment is a standard part of modern nitrous oxide equipment for laboring women.

Apoptosis: Another concern that has been expressed is that of apoptosis, the type of natural cell death that protects us from cancer, but can be a problem when taking place unnaturally. Unlike the real-world issue of occupational exposure to nitrous oxide, this effect has only been seen in laboratory animal studies at doses approximately 50 times that a laboring woman would ingest, a dose women in labor would never receive. (In fact, hyperbaric chambers had to be used to deliver the continuous, six-hour superatmospheric doses used in these experiments, since it is impossible to achieve a dose this high at normal atmospheric pressure.) Since many/most drugs in use have much more serious effects (e.g., death) at far lower than 50X effective-doses, this actually reflects the safety of nitrous oxide, especially compared with other analgesics.

Mild analgesia: Many feel that the reason for nitrous oxide's lack of availability here is that it is only a mild-to-moderately effective form of analgesia, in contrast to the very strong effects of an epidural. Judith Bishop, a midwife who works with nitrous oxide at the UCSF Moffitt hospital in San Francisco, states that "Not all laboring women who try it find it useful. Those who do either report reduced pain or acknowledge they are still in pain but care less about it." There is a prevalent idea that women do not want a mild form of pain relief that is only somewhat, rather than 100%, effective, but this presupposes that all women want 100% pain relief, unless they want to be 100% drug-free, and does not acknowledge the true diversity of women and their birth wishes.

Honoring Birth Wishes

Laboring women are often grouped together as one homogenous bloc, but in fact, the birth wishes of pregnant women are as diverse as the women themselves. With respect to pain relief, many women do want complete anaesthesia. "Knock me out -- I don't want to feel anything!" is a common refrain for many pregnant mothers-to-be. For these women, the highly medicalized birth options available in the U.S. are perfect. Complete anaesthesia through an epidural can enable an easy birth, and many mothers have been quite happy with this option.

At the other end of the spectrum are women who want a completely unmedicated birth, with no drugs of any kind. This option is becoming increasingly available, through alternative birthing centers, home-birth midwives, and more progressive, patient-centered hospitals. Many health professionals believe that all women are at either one or the other end of this spectrum.

However, there are other women who want to have a birth that is as natural as possible, but also would like "just a little" pain relief to help them achieve their goal. This is the strength of nitrous oxide. As midwife Judith Rooks states, "Nitrous oxide is not right for every woman during labor, but it is wonderful for some women."

Dr. Claudia Copeland holds a Ph.D. in molecular and cellular biology, with a tropical medicine emphasis, including the equivalent of a masters' degree in public health. She has given birth naturally twice, and would like to increase the availability of information for other women interested in minimizing excessive medical intervention for childbirth.