As previously written in the blog I wrote about labor coping strategies, the most common pain management options during labor in this country include IV opioid or epidural medication. Recently however, an additional option became available at St. Mary's here in Madison- nitrous oxide. Read on to learn more about the history of the use of "laughing gas" in labor, how it works, the benefits, the risks, and what the experts are saying.
Nitrous oxide has been used to manage pain for dental procedures since the mid 1800s, and is a common option for labor pain management in several countries, including the UK, Finland, Sweden, Canada, Australia, and New Zealand. While it was once a more common option in the United States as well, its popularity waned after the introduction of the epidural in the 1970's. Perhaps due to the rise in interest in low-intervention birth, as well as the unique benefits of nitrous oxide during labor, its popularity is now increasing once again in the US. According to this NPR article published in early November 2016, up until 2011, only a couple of hospitals in the United States offered nitrous oxide to women in labor. Per Porter Instrument, maker of Nitronox, a brand name for the 50/50 nitrous oxide/ oxygen mix, nearly 300 hospitals and birth centers now offer it, and recently, nitrous oxide became an available option at St. Mary's here in Madison.
How it Works
Sometimes referred to as "laughing gas" because of its euphoric effects, the mix of 50% nitrous oxide and 50% oxygen, is an anesthetic and analgesic gas. The laboring woman is provided a mask to use at her discretion, and inhales the gas just prior to or during contractions to help manage pain. According to this article, by the Agency for Healthcare Research and Quality, it is helpful for both relieving pain and anxiety.
The mechanism of action of nitrous oxide is thought to be an increased release of endorphin, dopamine, and other natural pain relievers in the brain, which modulate pain stimuli via descending spinal cord nerve pathways. Nitrous oxide does not completely relieve the pain of labor but creates “diminished pain, or a continued awareness of pain without feeling bothered by it.”5 Nitrous oxide also has an antianxiety effect, which may be helpful if laboring women are restless and doubt their ability to cope, emotions that are not uncommon, especially during transition.
While compared to the epidural which may block pain entirely, nitrous oxide's ability to relieve pain is less; however, there are several benefits to its use as compared to the more commonly used pain medication options. It has a rapid onset and short duration of action, so those who experience side effects such as nausea or vomiting, or who decide its pain relief is inadequate can discontinue use and move onto another option. Mobility and positioning options are not limited with the use of nitrous oxide, and it does not require any additional monitoring or a urinary catheter. Also, newborn alertness and responsiveness during the important early period of maternal-infant bonding and early effective breastfeeding are unaffected, according to the American College of Nurse-Midwives.
Per this article, by the American Pregnancy Association, the side effects of nitrous oxide use are sedation, dizziness, nausea and vomiting. In terms of risks to the baby, it is known that nitrous oxide, like other anesthetic agents, can cross the placenta; however, as stated in this article, published in Reviews in Obstetrics and Gynecology "The use of N2O as a labor analgesic in the United Kingdom has produced a long track record of safe outcomes for both mother and child." And according to this article, published in the Journal of Midwifery and Women's Health in 2011, "Nitrous oxide labor analgesia is safe for the mother, fetus, and neonate and can be made safe for caregivers. It is simple to administer, does not interfere with the release and function of endogenous oxytocin, and has no adverse effects on the normal physiology and progress of labor."
Not that there haven't been questions raised about potential risks. Most recently, concerns have stemmed from apoptosis (brain cell death) seen in in utero and newborn animal brains as a result of exposure to nitrous oxide. These studies used prolonged exposures to very high doses of nitrous oxide, which limits applicability to the clinical setting; however as suggested in this article, Dr. Mark Zakowski, Chief of Obstetric Anesthesiology at Cedars-Sinai Medical Center in LA, even though transient exposure of nitrous oxide is unlikely to cause harm in humans, perhaps more high quality studies in animals and humans are needed to answer the long-term safety and developmental effects of nitrous exposures in mom and babies.
What Do the Experts Say?
According to this position paper by the American College of Nurse-Midwives, nitrous oxide is "an inexpensive, simple, reasonably safe, and effective analgesic. It is important that
midwives know about N2O analgesia and be able to offer it to women during labor."
The American College of Obstetricians and Gynecologists have not come out with an official position. According to the NPR article, Dr. Laura Goetzl, a professor at Temple University's Lewis Katz School of Medicine in Philadelphia, and member of the American College of Obstetricians and Gynecologists, helped draft the College's 2002 guidance about analgesia for labor, which, she says, "did not discuss nitrous oxide as an option since its use in the U.S. was exceedingly rare at the time." She adds, "However, I can speak as an expert on obstetrical analgesia that it is a safe and reasonable option. We are actually currently trying to add a service to our hospital."
The American Society of Anesthesiologists reviewed research related to the use of nitrous oxide in labor in 2012, and while they state that "inhaled nitrous oxide analgesia for labor has been used for several decades in the United Kingdom with good safety outcomes for both mother and child", they also state that "Appropriate patient consent should be obtained and in particular reflect the possibility of long term adverse effects on child neurologic development."
As I see it, as with many decisions one can make during their birth planning, there are benefits and potential risks to consider when looking at incorporating the use of nitrous oxide in your birth, and no cut and dry right answers or one size fits all. The good news is that if you are birthing at St. Mary's you now have an additional choice, and I always think more choice is a good thing.