Nitrous oxide gets used by the majority of women laboring in England and Scandinavian countries and for about one in five deliveries in Canada but never really caught for labor analgesia in the United States, with epidurals taking over instead, Rooks explained.
She started writing articles to that effect in midwifery journals in 2007, which brought on a deluge of interest and creation of an Internet list serve.
"I want to expand access," she told MedPage Today. "If epidurals weren't available I would want to expand access to them. I believe women should have a choice. I focused on nitrous oxide because it's missing from what's available to women in the U.S."
And that is a message that resonates with midwives and pregnant women.
"The resurgence is being driven by midwives," Serat said. "We spend lots of time with women in labor. Lots of time. … It's just nice to have as many tools as you can possibly have."
Consumer interest is likely to drive the rest of the progress, once hospitals see nitrous as a factor that makes them competitive in attracting deliveries to their center, Bishop noted.
That's been the case at Vanderbilt, noted obstetric anesthesiologist Sarah Starr, whose center has purchased the equipment and is on the threshold of becoming the fourth to offer nitrous oxide for labor.
"In our department there was an initial thought of why would anybody want anything other than an epidural because an epidural obviously provides superior pain relief," she told MedPage Today. But "we have a very great patient interest in it. Women are very interested in having different options."
Nitrous oxide is no replacement for epidurals, Palmer cautioned in an interview supervised by ASA public relations staff.
"It's just not that great a pain reliever," he told MedPage Today. "Even in places that embrace it I think a lot of patients would say 'It's not working that well, now I'll have the epidural.'"
Other factors can come into play as well, such as for Jaeger, who had to switch to an epidural to stop her premature pushing response that threatened to lead to a C-section.
"It's not one size fits all," Bishop said. "More choices is a good idea."
Labor pain differs from the sort managed in other areas of medicine, noted Bishop, who has become one of the nation's go-to experts due to the scarcity of obstetric experience with nitrous oxide here.
Women in labor know the pain is normal and going to come to an end, and not all want to lose all sensation of the birth, she explained.
"This is not throwing them scraps," Rooks argued. "Not everybody wants the same thing."
Rather than being a turf issue, obstetric anesthesiologists and nurse midwives have a common goal, according to Starr.
"We want to provide the safest and best care for all our patients," she said. "As an anesthesiologist, it has more to do with really coming to grips with the fact that just because something provides complete pain relief doesn't mean it's the best option for all women."
One major curtail on the fledgling field's momentum is the lack of infrastructure, noted Palmer.
"Most facilities simply aren't prepared to offer nitrous oxide for labor analgesia," he said.
The FDA has not approved the premixed oxygen and nitrous oxide tanks that are used in other countries, and production of the fixed ratio equipment to mix the separate gases stopped due to lack of sales.