We selectively searched the PubMed database for
articles published from 1966 to 2012 containing the key words “preterm delivery,” “preterm birth,”
“tocolysis,” and “tocolytic therapy” in order to identify
all relevant randomized controlled trials, systematic
reviews, and meta-analyses. The search was limited to
studies in human beings and to publications in English
or German. The current guidelines of the European,
British, and American obstetric societies were also
considered in the analysis