Comparison 9. Hypnosis plus audio CD/tape versus hypnosis no audio CD/tape versus nurse/audio CD only (subgroup analysis).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Use of pharmacological pain relief/anaesthesia	6	2499	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.85, 1.17]
1.1 Hypnosis plus audio CD/tape	4	2173	Risk Ratio (M‐H, Random, 95% CI)	0.90 [0.73, 1.10]
1.2 Hypnosis, no audio CD/tape	2	107	Risk Ratio (M‐H, Random, 95% CI)	1.50 [0.57, 3.93]
1.3 Nurse/audio CD only	1	219	Risk Ratio (M‐H, Random, 95% CI)	1.01 [0.86, 1.18]
2 Spontaneous vaginal birth	6	2504	Risk Ratio (M‐H, Random, 95% CI)	1.09 [0.95, 1.26]
2.1 Hypnosis plus audio CD/tape	4	2178	Risk Ratio (M‐H, Random, 95% CI)	1.02 [0.90, 1.15]
2.2 Hypnosis, no audio CD/tape	2	107	Risk Ratio (M‐H, Random, 95% CI)	1.64 [0.79, 3.42]
2.3 Nurse/audio CD only	1	219	Risk Ratio (M‐H, Random, 95% CI)	0.97 [0.77, 1.22]