Preterm birth (PTB) is a leading cause of perinatal mortality and morbidity. Although the pathogenesis of preterm labour (PTL) is not well understood, there is evidence about the relationship between maternal psychological stress and adverse pregnancy outcomes. Relaxation or mind-body therapies cover a broad range of techniques, e.g. meditation, massage, etc. There is no systematic review investigating the effect of relaxation techniques on preventing PTL and PTB. This review does not cover hypnosis as this is the subject of a separate Cochrane review.