Terbutaline

Preterm births account for 75 to 80 percent of perinatal deaths. Up to 30 percent of infants who survive may have persistent mental, neurologic or respiratory dysfunction. Parenteral tocolytic therapy has been used with reasonable success to stop premature uterine contractions. How and associates performed a prospective, randomized trial to determine whether patients benefit from use of maintenance oral terbutaline after successful intravenous tocolysis to prevent subsequent premature uterine contractions.

The study included a total of 184 patients with preterm uterine contractions. After contractions were successfully stopped with magnesium sulfate therapy, the patients were discharged from the hospital to receive continuous bed rest either with or without oral terbutaline (5 to 10 mg every four to six hours). Patients were assigned to one of four groups: (1) those with a Bishop score of 5 or more who were given oral terbutaline, (2) those with a Bishop score of 5 or more who were not given oral terbutaline, (3) those with a Bishop score of less than 5 who were given oral terbutaline, and (4) those with a Bishop score of less than 5 who were not given oral terbutaline. Oral terbutaline was discontinued at 37 weeks of gestation. Home uterine monitoring devices were not used in the study

No statistically significant differences were observed in maternal age, parity, race, duration of intravenous tocolysis or duration of hospital stay among the four groups. No significant differences occurred in the mode of delivery, readmissions, or the number of unscheduled hospital visits among the groups. Of the patients in group 1,16.0 percent subsequently presented with preterm premature rupture of the membranes (PROM); in group 2,5.7 percent had preterm PROM; 2.4 percent in group 3 had preterm PROM, and 5.0 percent in group 4 had preterm PROM. Compared with patients with a Bishop score less than 5, patients with a Bishop score of 5 or more had a significantly lower gestational age at delivery and lower percentage of deliveries at 37 weeks or later. However, no significant differences in these characteristics were found when group 1 was compared with group 2 and when group 3 was compared with group 4. Culture results did not differ significantly among the groups.

The neonatal outcome demonstrated no differences with respect to neonatal morbidity. A comparison of patients randomized to the oral terbutaline arm and the arm not receiving oral terbutaline revealed no differences in relevant maternal clinical characteristics or in pregnancy and neonatal outcome.

The authors conclude that oral terbutaline maintenance therapy does no improve pregnancy outcome in patient who have had successful intravenous tocolysis for premature onset of labor. (How HY, et al. Oral terbutaline in the outpatient management of preterm labor. Am J Obstet Gynecol 1995;173:1518-22.)

EDITOR'S NOTE: Premature births exact an enormous toll on families and society at large. Numerous nonrandomized trials have pointed to the efficacy of tocolysis in stopping premature uterine contractions. However, its efficacy in effectively changing pregnancy outcome has not been proven. Findings of this randomized study demonstrate that oral terbutaline does not prolong pregnancy and is no better than bed rest alone. The efficacy of other tocolytics, such as nifedipine and indocin, should be evaluated in the future.

COPYRIGHT 1996 American Academy of Family Physicians
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