Objective: The purpose of this study was to compare terbutaline and nitroglycerin for acute intrapartum fetal resuscitation.
Study design: Women between 32-, 42 weeks' gestation were assigned randomly to 250 microg of terbutaline or 400 microg nitroglycerin intravenously for nonreassuring fetal heart rate tracings in labor. The rate of successful acute intrapartum fetal resuscitation and the maternal hemodynamic changes were compared. Assuming a 50% failure rate in the terbutaline arm, we calculated that a total of 110 patients would be required to detect a 50% reduction in failure in the nitroglycerin group (50% to 25%), with an alpha value of .05, a beta value of .20, and a power of 80%.
Results: One hundred ten women had nonreassuring fetal heart rate tracings in labor; 57 women received terbutaline, and 53 women received nitroglycerin. Successful acute resuscitation rates were similar (terbutaline 71.9% and nitroglycerin 64.2%; P = .38). Terbutaline resulted in lower median contraction frequency per 10 minutes (2.9 [25-75 percentile, 1.7- 3.3] vs 4 [25-75 percentile, 2.5- 5]; P < .002) and reduced tachysystole (1.8% vs 18.9%; P = .003). Maternal mean arterial pressures decreased with nitroglycerin (81-76 mm Hg; P = .02), but not terbutaline (82-81 mm Hg; P = .73).
Conclusion: Although terbutaline provided more effective tocolysis with less impact on maternal blood pressure, no difference was noted between nitroglycerin and terbutaline in successful acute intrapartum fetal resuscitation.