Forty-six women in active labour who developed fetal distress requiring abdominal delivery were randomized to receive 0.25 mg of terbutaline (subcutaneously) or magnesium sulphate as a 4-g bolus (intravenously) to decrease uterine activity. The terbutaline-treated group in contrast to the magnesium sulphate-treated group had reduced uterine activity as measured by Montevideo units (p < 0.002). This decrease in uterine activity was noted more rapidly in all 23 patients who received terbutaline, 1.8 +/- 0.74 minutes compared to 7.5 +/- 2.1 minutes in the 16 of 23 patients (magnesium sulphate-treated women) in whom a decrease in uterine activity occurred (p < 0.001). Umbilical cord arterial blood pH at delivery was less than 7.20 in only 2 of the 23 patients treated with terbutaline versus 7 of the 23 in the magnesium sulphate-treated group. We conclude that terbutaline is an effective and more rapid-acting tocolytic agent to arrest uterine activity prior to delivery for fetal distress.

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