Objectives: The Vanderbilt Evidence-based Practice Center systematically reviewed evidence addressing the use of nitrous oxide for the management of labor pain.
Data Sources: We searched the MEDLINE®, Embase, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases for articles published in English.
Review Methods: We excluded studies that did not address a Key Question, were not original research, or had fewer than 20 participants. We identified a total of 58 publications, representing 59 distinct study populations: 2 of good quality, 11 fair, and 46 poor.
Results: Inhalation of nitrous oxide provided less effective pain relief than epidural analgesia, but the quality of studies was predominately poor. The heterogeneous outcomes used to assess women's satisfaction with their birth experience and labor pain management made synthesis of studies difficult. The strength of evidence was insufficient to determine the effect of nitrous oxide on route of birth. Most maternal harms reported in the literature were unpleasant side effects that affect tolerability (e.g., nausea, vomiting, dizziness, and drowsiness). Apgar scores in newborns whose mothers used nitrous oxide were similar to those of newborns whose mothers used other labor pain management methods or no analgesia. Evidence about occupational harms and exposure was limited.
Conclusions: The literature addressing nitrous oxide for the management of labor pain has few studies of good or fair quality. Synthesis of effectiveness and satisfaction studies is challenging because of heterogeneous interventions, comparators, and outcome measures. Research assessing nitrous oxide is needed across all of the Key Questions addressed: effectiveness, women's satisfaction, route of birth, harms, and health system factors affecting use.