**2. Material and methods**

Articles have been searched in *Medline* and *Pubmed* database as well as in the *Cochrane Database of Systematic Reviews*. The search has been limited to those studies in human beings and articles in English or Spanish developed between 1995 and 2007. Current clinical practice guidelines (from the –American, British, Canadian and Spanish national associations of obstetricians and gynecologists on external version and breech presentation have also been reviewed. Key words: Breech, cephalic version, external version, adverse event "and" cephalic version.
