Table 6. Applicability of the body of evidence.

Population	The majority of evidence pertained to women with recurrent preterm labor and singleton gestation in the United States. Very little information was reported about the study populations' demographic and clinical characteristics. Nine of 14 studies (64 percent) included women judged to be in labor on account of persistent contractions and cervical change. The definition of labor was unclear in other studies. Among the studies that suggested that the pump was efficacious, 50 percent reported cervical change and contractions as part of the definition of labor while 50 percent did not report how labor was defined.
Intervention	Although there were gaps in reporting, the intervention generally did not pose any serious limitations to applicability. Very few details were reported on cointerventions that could modify the effectiveness of therapy, such as administration of corticosteroids. In several studies, participants received specialized outpatient services from Matria Healthcare.
Comparison	Comparators included oral tocolytics, no treatment, and placebo.
Outcomes	Surrogate outcomes were the most commonly reported. Data on clinical outcomes, neonatal/maternal harms, and pump-related outcomes were sparse. Long-term outcomes have not been reported at all.
Timing of Outcomes Measurement	The absence of follow-up beyond delivery is a major limitation because important long-term outcomes have not been evaluated.
Setting	All studies were from the United States and participant data were acquired from a national database (Matria) or from single center sites. Women from the Matria database generally received a high level of care from an outpatient perinatal program. However, the distribution of regions from which patient data were included into the national database is unknown and information about the standards followed by the individual practice sites that provided obstetrical care was not reported. Similarly, for those studies that took place at single center sites, the standards of care followed at these sites are unclear.