Impact of therapeutic rest in early labor on perinatal outcomes: a prospective study

Abstract

Background: Pain and exhaustion in early labor are important to address, yet treatment options are limited. Therapeutic rest has existed for decades, although medication regimens and management strategies vary. In addition, there are little prospective data on perinatal outcomes and patient satisfaction to support and guide its use as an outpatient pain control option.

Objective: This study aimed to evaluate whether outpatient therapeutic rest in early labor using intramuscular morphine sulfate and promethazine is associated with differences in perinatal outcomes and to assess patient satisfaction with this therapy.

Study design: This prospective cohort study was conducted at a tertiary care academic medical center from September 2017 to April 2020. Participants presenting to the hospital for labor evaluation were offered therapeutic rest if they met the following criteria: reassuring modified biophysical profile, cervical dilation of ≤5 cm without contraindications to vaginal delivery, and plan to discharge home after evaluation. The primary outcome was subsequent hospital admission in active labor, defined as cervical dilation of ≥6 cm. Secondary outcomes included hospitalization duration and perinatal outcomes. The outcomes between participants who accepted therapeutic rest and those who declined it were compared. All P values were calculated using the Fisher exact test, and multivariable regression was used to adjust for potential confounding baseline variables with P<.2. In addition, a prespecified sensitivity analysis was performed, limiting subjects to nulliparous participants. Furthermore, postpartum surveys were administered to a subset of women who received therapeutic rest.

Results: Of the 82 individuals offered therapeutic rest and consented for the study, 66 (80%) accepted and 16 (20%) declined. Although the rate of active labor at admission to the labor and delivery unit in the treatment group was markedly higher (26% [17 of 66] vs 13% [2 of 16]), this difference was not statistically significant (P=.3) (adjusted relative risk, 1.87; 95% confidence interval, 0.44-7.89). Women who received therapeutic rest were less likely to require induction of labor compared with those who declined therapeutic rest (adjusted relative risk, 0.15; 95% confidence interval, 0.041-0.54). There was no difference between the groups in mode of delivery, epidural use, length of hospitalization, maternal complications, or adverse neonatal outcomes. These findings persisted in our prespecified sensitivity analysis, limiting the study to nulliparous participants. A subset (27 of 66 [40%]) of women were surveyed after receiving therapeutic rest, and all women (n=27) who were surveyed reported satisfaction.

Conclusion: There was no detectable difference in the primary outcome of active labor at admission between patients who accepted outpatient therapeutic rest and those who declined it. However, fewer participants in the treatment group eventually required induction of labor, and this group did not experience an increase in adverse perinatal outcomes. Among the participants surveyed, a high rate of treatment satisfaction was reported. This study suggested that therapeutic rest is a well-tolerated and effective option for outpatient pain control in early labor.

Trial registration: ClinicalTrials.gov NCT03539562.

Keywords: labor analgesia; labor pain; latent labor; morphine sleep; prodromal labor; protracted labor.