This systematic review aims to identify reviews of fetal fibronectin and transvaginal cervical length for predicting preterm birth, so that these could be appraised and the findings from good quality reviews highlighted. Reviews, rather than individual studies, are the basis for this systematic review because of the proliferation of reviews and the benefits of a single, consistent appraisal and assessment of evidence from these reviews, rather than further attempts to find and appraise the many individual studies in the literature. Potentially eligible reviews were sought primarily through searches of the electronic databases MEDLINE (1966-2005), EMBASE (1980-2005), CINHAL (1982-2005), Science Citation Index (1970-2005) and The Cochrane Library (Issue 3, 2005). Our systematic review consists of a description of the two factors that might be predictive of preterm birth and for which at least one relevant review was found. The scope and quality of the identified review(s) are described, and their conclusions and the strength of these conclusions discussed. Ten reviews were identified, of which seven were included in this systematic review of reviews. The quality of each review is assessed within the following domains; the extent of searching undertaken, description of study selection and inclusion criteria, comparability of included studies, assessment of publication bias, assessment of heterogeneity and conduct of sensitivity analyses. The reviews we identified show that cervicovaginal fetal fibronectin and transvaginal sonographic cervical length measurements are clinically useful factors in predicting preterm birth. Consideration might be given to the use of both the measurement of cervicovaginal fetal fibronectin and transvaginal sonographic assessment of cervical length to identify women at increased risk of preterm birth and, potentially, to improve the outcome for these women and their babies.