Background: Tocolytic agents inhibit contractions during the labor process. Subcutaneous terbutaline (SQ terbutaline) infusion by pump is used as a prolonged (beyond 48–72 hours) maintenance tocolytic following acute treatment of preterm contractions. The effectiveness and safety of this maintenance tocolysis have not been clearly established.
Objectives: To compare the benefits and harms of the SQ terbutaline pump with other tocolytics, conservative management, or placebo in specific populations of women with arrested preterm labor, and to explore confounding by level of maternal activity and care.
Data Sources: MEDLINE (1950 to April 1, 2011); Embase (1980 to April 1, 2011); CINAHL (1985 to December 7, 2009), the Cochrane Library (April 1, 2011), and the Centre for Reviews and Dissemination databases (January 2, 2010). We also reviewed grey literature.
Review Methods: We followed a prior systematic review protocol. Two reviewers independently included reports that investigated SQ terbutaline pump therapy in women between 24–36 weeks' gestation following arrest of preterm labor. We included noncomparative studies only for pump-related harms. Non-English records without an English abstract were excluded. We also excluded case reports but sought Food and Drug Administration (FDA) summaries of postmarketing surveillance data. One reviewer extracted data into a standardized electronic form and assessed study risk of bias and applicability. A second reviewer verified data.
Results: Two randomized trials, one nonrandomized trial, and 11 observational studies met inclusion criteria. In women with recurrent preterm labor (RPTL) and singleton gestation, the strength of evidence favoring the SQ terbutaline pump over oral tocolytics or no treatment is low for the outcomes of incidence of delivery at <32 weeks and <37 weeks, and mean days of pregnancy prolongation. In women with RPTL and twin gestation, the strength of evidence favoring the pump over oral tocolytics is low for neonatal death, incidence of delivery at <32 weeks, and mean days of pregnancy prolongation. Strength of evidence is insufficient for bronchopulmonary dysplasia, incidence of delivery <28 weeks and <34 weeks, and withdrawals due to adverse events. Observational studies of medium to high risk of bias showed the benefit of the SQ terbutaline pump for other surrogate outcomes, such as birth weight and neonatal intensive care unit (NICU) admission. Absent or inconclusive evidence addressed all other neonatal health outcomes, neonatal harms, maternal harms, and pump-related outcomes. An assessment of confounding by maternal activity and maternal care was not possible due to sparse data. Until 2009, several cases of maternal deaths and maternal cardiovascular events in association with terbutaline tocolysis have been reported to the FDA.
Conclusions: The evidence base consists of a small number of biased studies. A substantial body of evidence originated from one proprietary database. Although evidence suggests that pump therapy is beneficial as maintenance tocolysis, our confidence in its validity and reproducibility is low. While postmarketing surveillance has detected cases of serious harms, safety of the therapy remains unclear.