Association of Self-Administered Nitrous Oxide for Labor Analgesia With Maternal and Neonatal Process and Outcome Measures.

OBJECTIVE

To describe patterns of use of self-administered nitrous oxide (NO) during labor and to determine if maternal and neonatal process and outcome measures differ for women who use NO compared to women who do not use NO.

DESIGN

Retrospective, full-census, observational cohort.

SETTING

An upper midwestern U.S., urban, 75-bed quaternary perinatal center with more than 5,000 annual births.

PARTICIPANTS

The participants included two groups of women: 400 who used NO during labor and a comparison group of 6,733 who met NO eligibility but did not use NO.

METHODS

We used descriptive statistics to examine patterns of use of NO during labor between January 2015 and March 2017. We examined associations of NO with process (length of first and second stages of labor, time from hospital admission to birth, time from birth to hospital discharge, and total length of stay) and outcome measures (shoulder dystocia, instrumentation, vaginal lacerations, Apgar scores at 5 minutes, nursery disposition) using multivariate linear, logistic, and ordinal regression models.

RESULTS

Three percent (12/400) of women who used NO discontinued because of side effects. Among participants with vaginal births who used NO, 17.6% (62/352) used NO as the only form of pain medication during labor. We found no significant differences in maternal and neonatal outcome measures between the two groups. Among the process measures examined, we found a mean 2-hour-longer time from admission to birth and total length of stay in the NO group (p < .05) compared to the non-NO group.

CONCLUSION

Most participants who used NO (290/352, 82.3%) transitioned to other pain modalities during labor. Maternal and neonatal process and outcome measures were comparable relative to other pain management modalities, with the exception of longer time durations for two measures.