Intrathecal narcotics are associated with prolonged second-stage labor and increased oxytocin use

Safe and effective labor analgesia is an important part of obstetric care. Intrathecally injected narcotics (ITN) are an effective alternative to epidural anesthesia, and are perceived less likely to interfere with the course and outcome of labor. Data on their effects, however, are sparse and contradictory.

Our retrospective study compared labor length, oxytocin use, delivery type, maternal side effects, and neonatal outcomes among women who received ITN (n=100) and a group who received intravenous narcotics or no analgesia during labor (n=100). We randomly sampled medical records with stratification for parity and collected data through systematic chart review.

Women receiving ITN were more likely to be white. They experienced longer second-stage labors (73 minutes vs 40 minutes, P=.000) and used oxytocin twice as often. These differences remained significant after controlling for potential confounding factors. ITN use was also associated with a trend toward more cesarean sections (7% vs 1%, P=.06). More of the women receiving ITN required urinary catheterization (25% vs 5%, P=.000) and experienced significant pruritus (10% vs 0%, P=.001). Neonatal outcomes were similar for both groups.

In our retrospective study, ITN use was associated with a significant prolongation of second-stage labor, which may be clinically relevant for women having their first child. ITN were also associated with increased oxytocin use and a trend toward more cesarean births. Whether these relationships are causal or a proxy for more difficult labors is a question for future prospective studies.