Study of the Effects of Intravenous Injection of Hyoscine on Parturition (Labor)

Despite wide use of hyoscine by midwives and doctors as an adjunct to labor, the obstetrics literature contains few references to the effect of this drug. This study was a double blinded, randomized controlled trial of primigravidas in Iran to determine the effects of hyoscine intravenous injection on parturition (labor).

One hundred primigravidas in uncomplicated spontaneous labor with cervical dilation less than 4 cm and cervical effacement < 50% were randomly assigned into two groups the experimental group ( N = 50 ) receiving 20 mg hyoscine and the control group ( N = 50 ) receiving placebo, with predetermined codes injected at the beginning of the active phase of labor. The groups were compared for labor progress, fetal tachycardia and bradycardia after 0.5 and 1h of injection, Apgar score and birth weight. Statistical methods for normally distributed variables included 2- tailed student T test and chi- square analysis. The accepted level of significance was p < 0.05.

The two groups were similar in respect to maternal age, gestational age , initial cervical effacement & dilation and mean birth weight. The mean change in the cervical effacement and dilation after 1 & 2 h of injection was significantly higher in those receiving hyoscine (p< 0.0001). There was a significant difference in the duration of active phase and second stage of labor in the two groups ( p < 0.0001 ). Fetal tachycardia and bradycardia occurred more frequently in patients in the hyoscine group as compared to the control group but the difference was not significant. The difference between the mean first and fifth- minute Apgar score was not significant, too.

This small study suggests the benefits of a single dose of hyoscine for labor progress and represents the first attempt to evaluate this medication. However, larger randomized studies are needed to establish the efficacy, safety, and optimal dose of hyoscine .