The experience and role of the companion during normal labor and childbirth: a systematic review of qualitative evidence - Hoga, Luiza Akiko Komura; Gouveia, Luciana Magnoni Reberte; Manganiello, Adriana; Higashi, Aline Baraldi; Roth, Fernanda de Souza (JBI Database of Systematic Reviews and Implementation Reports, 2011)