Much like a mother’s belly in the ninth month of pregnancy, the use of nitrous oxide has ballooned since the University of Colorado Hospital joined a small number of U.S. hospitals offering “laughing gas” to its laboring patients in 2014.

Then a “pioneer” of sorts, the hospital became the first in the Rocky Mountain Region to provide the alternative, which is more common in this country in a dentist office than in a birthing room.

Now, with more than 1,000 hospitals and 300 birth centers in the country having followed suit, research on the Anschutz Medical Campus continues CU’s trailblazing efforts. Studies looking at everything from the Mile High altitude’s effect on nitrous oxide to how often women who choose the gas convert to other pain management options, such as epidurals, are underway.

Use of nitrous oxide re-emerges in U.S. birthing rooms

“Nitrous oxide used to be quite popular in the United States through the mid-century,” said Priscilla Nodine, PhD, CNM. “Then there was the advent of epidurals, and its use went completely away in the United States,” she said of the inhaled gas during a Sept. 6 College of Nursing Research and Scholarship Symposium session. “Now it’s coming back into the mix of possible options.”

Nodine and Jessica Anderson, DNP, CNM, director of CU Nursing’s Midwifery Services, shared research findings on the analgesic, which remains highly common in European countries. The Anschutz Medical Campus helped form and now houses a multi-institutional database, collecting 237 data points on nitrous oxide use during labor over three years.

Less potent than the dentist’s version, nitrous oxide in the birthing room contains 50% nitrous oxide and 50% oxygen, a mixture too weak to cause anesthetic effects. Instead, the colorless, non-flammable gas eases laboring moms’ pain largely by reducing their anxiety.

Diverse group opts for gas in CU Nursing study

In their study, Nodine and Anderson looked at satisfaction rates of the 436 women who chose nitrous oxide during labor and delivery, the demographics of the group, and the predictors of conversion rate to epidurals. Consistent with other similar academic hospitals, about 10% to 13% of women opted for the gas.

“It’s actually a very diverse group of women who choose to use nitrous oxide at the University of Colorado Hospital in parity, ethnicity, race and marital status,” Nodine said. Women are in charge of nitrous oxide intake during labor, inhaling puffs through a mask whenever they feel the need.

Overall, patients were moderately satisfied with the option, which studies suggest are safe for mom and baby, Nodine said. “Side effects were rare and not life-threatening, and APGAR scores were good (the scale used in rating the health of a newborn).”

Study finds spike in epidural conversion with intervention

Also consistent with other studies of similar hospitals, 63% of the participants converted to epidurals, Nodine said.

Predictors were medical augmentation (a woman already in labor receives labor-inducing medication) and labor induction (a woman not in labor has labor induced). Both groups were three times more likely to convert. Women with prior C-sections seeking a vaginal birth were six times more likely to convert to epidurals after nitrous oxide use.

“The thought regarding these findings is that induced and augmented labors are more likely to take longer, requiring more support in getting to the finish line of holding a baby,” Anderson said.

Those who delivered without converting to analgesic or anesthetic options were often women whose labor progressed relatively rapidly.

Researcher: Studies seek to inform, support choice

Although their studies are important largely because C-section rates in this country are high, Anderson noted that conversion rates do not equal failure rates.

“Families have different goals for their experience,” she said. “For some, that is to get an epidural. For others, it is to avoid an epidural if possible. Both examples can still benefit from the use of nitrous oxide.”

For instance, women who opt for epidurals are generally immobile, and the option of nitrous oxide allows them to be mobile longer before making that choice, she said.
The researchers are just delving into a study on high altitude’s effects on nitrous oxide, with many of neighboring intermountain hospitals’ questioning if it influences effectiveness of the gas, Anderson said. Preliminary results suggest that it does.

“The thought is the partial pressure is lower at higher altitudes and most likely decreases the concentration of gasses and increases patient likelihood to convert to another modality.”

In the study, women at sea-level hospitals were more likely to stick with nitrous oxide, even with higher rates of side effects, such as nausea and dizziness. Individuals at altitude were most likely to convert due to inadequate pain relief, Anderson said, explaining that the higher rate of side effects at sea level suggests that the nitrous oxide was more effective.

Other studies, including one that looks at breastfeeding rates after births with nitrous oxide use, are also in the works, Anderson said. “It’s important to us as providers to understand the implications and how nitrous oxide works so we can counsel patients appropriately and ultimately support patients’ choices.”

• Has no effects on normal physiology and progress of labor.
• Does not disrupt release of oxytocin and therefore does not affect newborn alertness.
• Does not affect breastfeeding.
• Does not increase the need for newborn resuscitation.
• Does not alleviate labor pain but relaxes and decreases perception of pain.
• Allows women the choice in how much to use.
• Is easily discontinued with effects disappearing in five minutes.
• Can cause dizziness, nausea and vomiting.