A randomized controlled trial by researchers from Oslo University Hospital examined whether a self-administered practice of relaxation techniques, positive affirmations and guided imagery in the final part of pregnancy resulted in a positive impact on giving birth; and additionally, whether using a CD with a booklet, with no previous training or practitioner assistance, could be effective.
Outcome measures were monitored both during and after delivery. During delivery, pain and anxiety were measured at different stages of birth.  Post-delivery measures included well-being (Edmonton Scale 0-10, where 10 is the worst), pain, anxiety, Apgar score, duration of birth, complications and anesthesia/analgesic use.

Adherence of those in the CD-intervention group was checked with by having them log and report how many times they practiced the techniques.
Results showed that the CD-intervention group had a significantly better score on total well-being, as measured by the ESAS (0-10) Edmonton Scale, as compared with the controls.

Gedde-Dahl M, Fors EA. Impact of self-administered relaxation and guided imagery techniques during final trimester and birth. Complementary Therapies in Clinical Practice. 2012 Feb;18 (1):60-5. Epub 2011 Sep 7. [email protected]