Nitrous Oxide Use for Pain in Labor, Conversion to Neuraxial Anesthesia and Birth Outcome

Susan DeJoy; Candice Killeen; Donna Jackson-Köhlin; Audrey Psaltis; Alexander Knee

doi:10.1111/jmwh.13636

Nitrous Oxide Use for Pain in Labor, Conversion to Neuraxial Anesthesia and Birth Outcome

J Midwifery Womens Health. 2024 Apr 28. doi: 10.1111/jmwh.13636. Online ahead of print.

Authors

Susan DeJoy^{1

2}, Candice Killeen^{3

4}, Donna Jackson-Köhlin^{1

2}, Audrey Psaltis^{1

2}, Alexander Knee^{5

6}

Affiliations

¹ Division of Midwifery, Baystate Medical Center, Springfield, Massachusetts.
² Department of Obstetrics and Gynecology, UMass Chan Medical School - Baystate, Springfield, Massachusetts.
³ Midwifery Education Program, Baystate Medical Center, Springfield, Massachusetts.
⁴ Eden Birth and Wellness, Rogers, Arkansas.
⁵ Epidemiology/Biostatistics Research Core, Office of Research, Baystate Medical Center, Springfield, Massachusetts.
⁶ Department of Medicine, UMass Chan Medical School - Baystate, Springfield, Massachusetts.

PMID: 38678432
DOI: 10.1111/jmwh.13636

Abstract

Introduction: A variety of labor pain management options is essential to patients and their care providers. Inhaled, patient controlled nitrous oxide (N₂O) is a valuable addition to these options. The purpose of this study was to examine laboring patient, newborn, and provider characteristics associated with N₂O use for pain relief in labor and to examine the association between N₂O, conversion to neuraxial analgesia, and cesarean birth.

Methods: This was a retrospective observational cohort study of the first year of N₂O use in one large academic medical center. Patients at least 37 weeks' gestation who were admitted for labor with intended vaginal birth from August 1, 2018, to June 30, 2019, were included (N = 2605). Laboring patient and newborn factors and their relationship to N₂O use were calculated as unadjusted and adjusted relative risks (RRs). Poisson regression was used to model the association between N₂O use and subsequent use of neuraxial analgesia and type of birth for both nulliparous and multiparous patients.

Results: Overall, 20.2% of patients used N₂O during labor. Multiparous patients were 24% less likely to use N₂O than nulliparous patients (RR, 0.76; 95% CI, 0.69-0.84). Use of N₂O did not differ significantly between patients cared for by midwives compared with patients cared for by physicians (RR, 0.95; 95% CI, 0.90-1.00). In multivariable modeling, N₂O use in multiparous patients was associated with a 17% decrease in use of neuraxial analgesia (RR, 0.83; 95% CI, 0.73-0.94). There was no association between N₂O use and use of neuraxial analgesia in nulliparous patients (RR, 0.99; 95% CI, 0.93-1.06). N₂O use was not associated with cesarean birth in either group.

Discussion: N₂O is an important pain management option for laboring patients and those who care for them. Study results may assist midwives, physicians, and nurses in counseling patients about analgesia options.

Keywords: intrapartum pain; labor analgesia; neuraxial analgesia; nitrous oxide.