Terbutaline Studies

Several factors should be considered when comparing studies that test the effectiveness of any medication. In general, the best studies (also known as experiments) attempt to control as many biases and outside variables as possible. They do this by ensuring a sufficient number of test subjects and through randomization, double-blind and placebo-controlled groups. For each study listed, the following data have been provided to help with comparison.

Number of women
In general, more test subjects are preferable. The larger the number of test subjects, the more significant the observation. More test subjects also reduce the margin of error. For example, it's hard to reach conclusions about studies that may only include 10 subjects. However, carefully controlled studies involving large numbers of test subjects are expensive, so researchers must make trade-offs in developing their research instrument. In addition, statistical principles ensure that if test subjects are randomly picked from a population, this smaller sample can be representative of the larger population.

Test subjects are randomly assigned to treatment and control groups. This reduces pre-existing group biases as well as researcher biases.

Double-blind study
Neither the subjects or the researchers know who is receiving the treatment under study. This reduces test subject and researcher biases.

Placebo-controlled group
This is considered the gold standard for experiments. Some test subjects receive a harmless, unmedicated preparation to test whether a treatment or drug works better than no treatment or drug at all.

Control group
A group that does not receive a treatment. It's not quite as controlled as a placebo-controlled group since members of a control group know they are not receiving a treatment. But it does provide a basis of comparing a treatment group to a non-treatment group.

Studies Showing Terbutaline To Be No Better Than Placebo or Control After 24-48 Hours
Studies Showing Terbutaline To Prolong Pregnancies

Studies Showing Terbutaline To Be No Better
Than Placebo or Control After 24-48 Hours

Lead Author Year # of Women Randomized Double-Blind Placebo Control Group TerbType
Howard 1982 33 yes yes yes yes IV, shots, pills
Cotton 1984 54 yes no yes yes IV vs. MgSO4
Parilla 1993 55 yes no no yes pills
How 1995 185 yes no no yes pills
Lewis 1996 203 yes yes yes yes pills
Guinn 1997 179 yes no no yes shot
Brown 1997 375 no no no yes pills
Wenstrom 1997 42 yes no yes yes pills & pump
Sciscione 1998 156 no no no yes shots, then pills
Guinn 1998 52 yes yes yes yes pump

Studies Showing Terbutaline To Prolong Pregnancies

Lead Author Year # of Women Randomized Double-Blind Placebo Control GroupTerb Type
Brown 1981 46 yes yes yesyes pills
Caritis 1982 92 yes no nono terb vs. ethanol
Kosasa 1985 99 yes no nono ritodrine vs. terb
Ingemarsson 1985 330 no no no no IV
Lam 1988 9 no no no no pump
Haspedis 1988 70 no no no no shots vs. IV, then pills
Fischer 1991 19 no no no no pump
Allbert* 1992 992 no no no no pump
Allbert 1994 64 no no no no pump vs. pills

*Study was conducted in conjunction with Tokos(known now as Matria), a terb pump distributor.

Study Citations, Summaries

Howard, T.E., et al., "A Double Blind Randomized Study of Terbutaline in Premature Labor," Military Medicine, 1982, Vol. 147, pp. 305-307.
This study of 33 women found no statistically significant difference between those women (N=15) treated with terbutaline and those treated with a placebo (N=18). The women treated with terbutaline received it by IV, then through shots for 24 hours, then orally. There was no difference between the groups in prolongation of pregnancy, birth weight, development of respiratory distress syndrome or infant survival.
Cotton, David B., et al., "Comparison of Magnesium Sulfate, Terbutaline and a Placebo for Inhibition of Preterm Labor: A Randomized Study," The Journal of Reproductive Medicine, 1985, Vol. 29, No. 2, pp. 92-97.
This study failed to find any significant difference in success between treatments of magnesium sulfate, terbutaline and a placebo in delaying labor for at least 48 hours. It involved 54 women who were randomized into the three types of treatment. Despite a trend toward greater effectiveness in the terbutaline group, there were no statistically significant differences between the three groups in delivery delay or gestational age at delivery. Two women, one taking magnesium sulfate and the other taking terbutaline, had to discontinue treatment because of severe side effects.
Parilla, Barbara V., et al., "The Efficacy of Oral Terbutaline After Intravenous Tocolysis," American Journal of Obstetrics and Gynecology, 1993, Vol. 169, pp. 965-969.
This study found the use of oral terbutaline after successful intravenous tocolysis with magnesium sulfate failed to reduce the rate of preterm birth. This was a randomized study that compared 28 women on terbutaline to 27 who did not receive terbutaline and were solely on bed rest. There were no statistically significant differences between the groups in respect to time gained, gestational age at delivery, greater than or equal to 37 weeks at delivery, recurrent preterm labor, recurrent uterine contractions alone, birth weight, special care nursery admissions or neonatal respiratory distress syndrome.
How, Helen Y., et al., "Oral Terbutaline in the Outpatient Management of Preterm Labor," American Journal of Obstetrics and Gynecology, 1995, Vol. 173, pp. 1518-1522.
Long-term oral terbutaline failed to improve patients' pregnancy outcome when compared to a control groups just on bed rest. All the women had been treated and stabilized with magnesium sulfate in the hospital. They were divided into two trial and two control groups based on the amount of cervical change. No statistically significant differences were found in number of hospital readmissions, number of unscheduled hospital visits, and neonatal outcomes. The gestational age at delivery and percent of deliveries at greater than or equal to 37 weeks were not statistically different when the control groups were compared to treated groups with similar cervical change.
Lewis, R., et al., "Oral Terbutaline After Parental Tocolysis: A Randomized, Double- Blind, Placebo-Controlled Trial," American Journal of Obstetrics and Gynecology, 1996, Vol. 175, pp. 834-837.
This study consisted of 203 women between 24 and 34 weeks 6 days gestation. They were randomized into two groups; one group took oral terbutaline (5 mg every four hours) until 37 weeks gestation and one group took a placebo until 37 weeks gestation. The women had their contractions arrested with intravenous preterm labor drugs before the study began. No difference was seen in the incidence of delivery at 1 week, median latency (time until delivery) mean gestational age at delivery or incidence of recurrent preterm labor. There was no difference in neonatal outcomes. The study reviewed the data of 96 women enrolled before 32 weeks gestation in a post hoc fashion and found that terbutaline may have prolonged these pregnancies, but the authors said more prospective research is needed.
Guinn, DA, et al., "Management Options in Women with Preterm Uterine Contractions: A Randomized Clinical Trial," American Journal of Obstetrics and Gynecology, 1997 October, Vol. 177 (4), pp. 814-818.
This study consisted of 179 women being treated for preterm labor who were randomized into three groups: one group was merely observed, the second group received intravenous hydration, and the third received one shot of terbutaline. It found that IV hydration was of no benefit. The one dose of terbutaline resulted in the shortest treatment time at the hospital but did not affect pregnancy outcome. There was no statistically significant difference in the outcomes when comparing the three groups (including mean gestational age at delivery, preterm delivery at less than 34 weeks, preterm labor delivery at less than 37 weeks and neonatal intensive care admissions).
Brown, HL, et al., "Tocolytic Treatment for Preterm Contractions with and without Cervical Changes," American Journal of Perinatology, 1997 August, Vol. 14 (7), pp. 405-409.
This study compared 200 women without cervical changes and 175 with cervical changes. In these two groups, a representative sample (92/200 without cervical changes and 115/175 with cervical changes) received oral terbutaline until 37 weeks gestation. There was no statistically significant difference in pregnancy prolongation between the groups of women who received oral terbutaline versus those who did not.
Wenstrom, Katherine D., et al., "A Placebo-Controlled Randomized Trial of the Terbutaline Pump for Prevention of Preterm Delivery," American Journal of Perinatology, 1997, Vol. 14 (2), pp. 87-91.
This study divided 42 women into three groups after their preterm labor was arrested with magnesium sulfate. One group received terbutaline by pump, one group received saline by pump (placebo group) and the third group received oral terbutaline. "Terbutaline by pump, saline by pump and oral terbutaline appear equivalent for the prevention of preterm delivery," the study said. There were no statistically significant differences between the groups in average age at delivery, repeat triage visits, average triage visits, IV tocolysis on a return visit, preterm delivery at less than 34 weeks, preterm delivery at less than 37 weeks and neonatal intensive care admissions.
Sciscione, Anthony, et al., "Tocolysis of Preterm Contractions Does Not Improve Preterm Delivery Rate or Perinatal Outcomes," American Journal of Perinatology, 1998, Vol. 15, No. 3, pp. 177-181.
This study found that 75 women who took tocolytics for preterm labor (in the hospital) did not have a better preterm delivery rate or better perinatal outcomes than 81 women in a control group who took no tocolytics and were observed. Most of the women taking magnesium sulfate and/or terbutaline shots were older patients with commercial insurance, while most of the control group were younger women on public assistance. Women received either magnesium sulfate or terbutaline at the discretion of the attending physician. Two women (2.7%) in the tocolysis group had to discontinue treatment with a particular drug because of adverse side effects (magnesium sulfate overdose and chest pain on terbutaline).
Guinn, Debra A., et al., "Terbutaline Pump Maintenance Therapy for the Prevention of Preterm Delivery: A Double-Blind Trial," American Journal of Obstetrics and Gynecology, 1998, Vol. 179, pp. 874-878.
This study found no statistically significant difference in mean time to delivery in groups of women taking terbutaline by pump versus groups of women on a saline solution by pump. This study involved 52 women at less than 34 weeks gestation who were experiencing preterm labor. All the women had their contractions arrested by magnesium sulfate before the trials began. There were no differences in the average gestational age at delivery. Nor were there statistically significant differences in the rates of preterm delivery at less than 34 weeks and less than 37 weeks; neonatal outcomes were similar.
Brown, Stanley and Tejani, Nergesh, "Terbutaline Sulfate in the Prevention of Recurrence of Premature Labor," Obstetrics and Gynecology, 1981, Vol. 57, pp. 22-25.
This study compared a group of 23 women who received terbutaline pills with a group of 23 that received a placebo until 38 weeks gestation. Both groups of women had their contractions quieted by IV ethanol before the experiment began. The women taking terbutaline had their pregnancies prolonged for a greater number of days, on average, than the placebo group. The terbutaline group also had fewer cases of respiratory distress syndrome in delivered babies. This study defined preterm labor as painful, regular contractions occurring at intervals of less than 5 minutes. Cervical effacement and dilation were not necessary to participate in the study. In addition, the study does not give a breakdown of how many women reached different gestational ages. It presents an overall pregnancy prolongation average in days.
Caritis, Steve et al., "A Comparison of Terbutaline and Ethanol in the Treatment of Preterm Labor," American Journal of Obstetrics and Gynecology, 1982, Vol. 183, pp. 183-190.
This study compared women experiencing preterm labor who were randomly assigned to receive either terbutaline or ethanol. Terbutaline was found to work better than ethanol in preventing further cervical dilation during the first 36 hours after treatment was started. Pregnancy was prolonged longer in the terbutaline group (15 plus or minus 4 days) than in the ethanol group (10 plus or minus 3 days). However, only 18 percent of the women in both groups made it beyond 36 weeks gestation.
Kosasa, Thomas et al.,"Ritodrine and Terbutaline Compared for the Treatment of Preterm Labor," Acta Obsetrics Gynecology Scandinavia, 1985, Vol. 64, pp. 421-425.
This study compared 99 women who were assigned to either a terbutaline or ritodrine treatment for preterm labor. Delivery was delayed 25.8 days in terbutaline subjects and 13.0 days in ritodrine subjects. Babies of terbutaline subjects weighed more than those of ritodrine subjects; more women (60 percent) achieved 36 weeks gestation on terbutaline than on ritodrine (39 percent). Eight percent of terbutaline subjects discontinued the study because of side effects; 2 percent of ritodrine subjects discontinued because of side effects.
Ingemarsson, Ingemar and Bengtsson, Bengt, "A Five-Year Experience with Terbutaline for Preterm Labor: Low Rate of Severe Side Effects," Obstetrics and Gynecology, 1985, Vol. 176, pp. 176-180.
This Swedish study found reviewed the records of 330 women treated with IV terbutaline for preterm labor. They were between 24 and 36 weeks pregnant when treatment was started. In gestations before the 30th week with intact membranes, half of the women (51.3%) had their pregnancies prolonged by greater than six weeks. Nine patients (2.7% of the 330) had to discontinue terbutaline because of severe side effects.
Lam, Fung, et al., "Use of the Subcutaneous Terbutaline Pump for Long-Term Tocolysis," Obstetrics and Gynecology, 1988, Vol. 72, pp. 810-813.
This study used the terbutaline pump in nine patients who had failed oral terbutaline therapy for preterm labor. The study found that the terbutaline pump prolonged pregnancies by an average of 9.2 weeks plus or minus 4.3 weeks. There were no significant complications.
Haspedis, Lynne, and Wolf, David, "Terbutaline in the Treatment of Preterm Labor: A Comparison of Intravenous and Subcutaneous Administration," Journal of the American Obstetrics Association, 1988, Vol. 88, pp. 489-493.
This study compared 55 women who received terbutaline shots for preterm labor with 15 women who received IV terbutaline for preterm labor. Both groups received oral terbutaline after contractions ceased. There was no statistically significant difference in the effectiveness of each terbutaline delivery method or in the frequency of side effects. The average prolongation of pregnancies was 7.1 weeks in the shots group with 6.6 weeks in the IV group. In addition, 29/70 (41%) of the women had adverse side effects with one woman discontinuing the drug.
Fischer, Janet and Kaatz, Brian, "Continuous Subcutaneous Infusion of Terbutaline for Suppression of Preterm Labor," Clinical Pharmacy, 1991, Vol. 10, pp. 292-296.
This study of 19 patients who were put on the terbutaline pump found that the pump prolonged pregnancies in 14/19 women. Eleven women (58%) delivered after more than 36 weeks gestation.
Allbert, John, et. al., "Subcutaneous Tocolytic Infusion Therapy for Patients at Very High Risk of Preterm Birth," Journal of Perinatology, 1992, Vol. 12, pp. 28-31.
This retrospective study reviewed the pregnancy data of 992 women at high-risk of preterm labor who were put on the terbutaline pump. The study was done in conjunction with Tokos (now known as Matria), the terbutaline pump distributor. The patients received IV preterm labor drugs to quiet their contractions and then were sent home on the pump. The pump therapy extended the pregnancies by an average of 38 plus or minus 23 days; the average gestational age at delivery was 36.3 plus or minus 2.6 weeks. The study did not mention what percentage of women reached certain gestational ages. No mention was made of side effects from the treatment.
Allbert, John, et al., "Tocolysis for Recurrent Preterm Labor Using a Continuous Subcutaneous Infusion Pump," Journal of Reproductive Medicine, 1994, Vol. 39, pp. 614-618.
This retrospective study compared 32 women who took terbutaline by pump to 32 women who took it in pill form. The study found that patients on the pump were more likely to deliver babies at term than patients on the pills; the pump patients also were less likely to fail preterm labor treatment. Twenty-one out of 32 patients on the pump delivered a term fetus versus 5/32 in the pill group.
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