Subcutaneous Fentanyl as a Viable Alternative to Intravenous Administration for Managing Labor Pain

In a multicenter, open-label randomized controlled trial, subcutaneous and intravenous (IV) fentanyl were found to be similarly effective for labor pain management with high maternal satisfaction rates and no significant adverse effects.

Labor pain is acknowledged as one of the most intense forms of pain a woman experiences, and while epidural anesthesia is highly effective, it has certain limitations, according to the study, making alternative pain management strategies necessary. Fentanyl, with its high analgesic potency and short-acting duration, could be a viable option, but large-scale trials comparing the effectiveness and safety of different administration routes for labor pain management have been limited.

In this study, participants (n = 226) were randomly assigned to receive either IV or subcutaneous fentanyl. Pain scores were evaluated before and after the administration of fentanyl at intervals of 5, 30, and 60 minutes following, and then hourly until delivery. An intention-to-treat analysis was applied.

Both routes of administration were associated with a reduction in pain scores from baseline to delivery. IV fentanyl led to a mean pain score decrease of -1.39 (95% CI, -1.62 to -1.17), while subcutaneous fentanyl demonstrated a mean decrease of -0.89 (95% CI, -1.24 to -0.05). The comparison between groups showed no statistically significant difference in pain reduction, with an overall mean difference of -0.35 (95% CI, -0.76 to 0.05).

Maternal satisfaction was also comparably high between the two groups, with rates of 89.4% for IV fentanyl and 93.8% for subcutaneous fentanyl, and there was no significant difference in satisfaction between the groups (relative risk, 0.95; 95% CI, 0.88-1.03). The study reported no serious adverse effects in either the mothers or neonates for either route of administration.

Key limitations included the open-label design, which could introduce bias, as well as the relatively short follow-up duration limited to delivery, which restricted insights into longer-term effects on mothers and neonates.

“Both intravenously and subcutaneously administered fentanyl were safe and significantly reduced pain from baseline to delivery among low-risk pregnancies,” the study authors concluded. “Maternal satisfaction with the childbirth experience was high regardless of the route of administration of fentanyl.”

Reference:

Duangkum C, Sirikarn P, Kongwattanakul K, et al. Subcutaneous vs intravenous fentanyl for labor pain management. Am J Obstet Gynecol MFM. 2024;6(4):101310. doi:10.1016/j.ajogmf.2024.101310