Complete relief of labour pain is not easily accomplished in all parturients because of the large number of variables that need to be controlled. The severity and quality of pain and its perception (Figure 58.1) depends on a combination of many factors which include the:
1. severity and duration of pain and its associated hormonal stress response (Chapter 33);
2. various methods of pain relief which are available to the patient;
3. quality and extent of coaching and education at antenatal classes (5);
4. personality of the mother and support persons;
5. cultural and ethnic background of the mother (1);
6. extent, nature and effectiveness of support offered to the mother by the partner and her attendants; and
7. degree and duration of fear, anxiety, fatigue, dehydration and nausea associated with the labour (1, 5).

The non-pharmacological methods of pain relief in labour include:
1. Prepared childbirth (Chapter 64);
2. Hypnosis;
3. Acupuncture;
4. Transcutaneous Electrical Nerve Stimulation (TENS)

Hypnosis:
Hypnosis is a state of altered consciousness in which, during a period of profound concentration, acutely enhanced responsiveness to suggestions occurs. Reduced awareness of the pain of labour is possible in this trance-like state. Unfortunately, the technique is most successful when a great deal of individual rapport with a particular hypnotist over many sessions has been established. Hypnosis requires considerable, time-consuming antepartum coaching. 15% of patients cannot be hypnotised. Even in those who can be hypnotised, the results have not been impressive.

Acupuncture:
Gate control and enkephalin-production theory have been applied to acupuncture but do not fully explain how it relieves pain in labour. Why subcutaneous insertion (and vibration, electrical stimulation or heating) of needles along 'energy pathways' (meridians) or at points of high A-beta (gate-closing) fibre concentration relieves pain is poorly understood. Acupuncture has not achieved widespread use because the acupuncture points for vaginal delivery pain have not been established. The pain relief obtained, without the additional use of significant doses of narcotics, is usually poor and inconsistent. The acupuncture needles also limit the parturient's mobility. Acupuncture is not suitable for rapid delivery (4).

Transcutaneous Electrical Nerve Stimulation (TENS):
Cutaneous application of electrical current can relieve pain. The mechanism by which this is achieved may be similar to that pertaining to acupuncture, i.e. release of endorphins or closure of the pain gate by A-beta stimulation. For relief of labour pain TENS is of limited value with, at best, a 44% patient acceptance and satisfaction rate (2). The electrodes over the dermatomes of T10 - L1 (1st stage stimulation) (9) and over the sacrum (late 1st and 2nd stage) transmit a 40-150Hz stimulus of 1-40 mA (1). TENS seems to be most useful when it is started in early labour and then mostly to relieve pain in the early first stage (1).

References:
1. Gatt SP and Lacy L Analgesia and anaesthesia in obstetrics. In: Handbook of Obstetrics and Gynaecology. (Leader L, Bennett M, Wong F, Eds) 4th ed. Chapter 8, Chapman and Hall Medical. In press, Mar 1996

2. Brownridge P, Wood M. Soothing the pain of childbirth. Flinders Media, Flinders Medical Centre. 1992

3. Lamaze F. Painless Childbirth - Psychoprophylactic methods. Pocket Book 1972

4. Chantigian R. Non-Pharmacological methods for pain relief in obstetrics. In: Clinics in Anesthesiology - Obstetric analgesia and anesthesia. Ostheimer GW Editor. WB Saunders, Philadelphia, 197-207 1986

In: Handbook of Obstetrics and Gynaecology. (Leader L, Bennett M, Wong F, Eds) 4th ed. Chapter 8, Chapman and Hall Medical. In press, Mar 1996.

5. Climie CR and Gatt SP. Analgesia and Anaesthesia in obstetric practice. In: Handbook of obstetrics and gynaecology. (Wren BG, Lobo RA, Eds) 3rd ed. , ch 8, Chapman and Hall medical pp 189-206. 1987

9. Augustinsson L, Bohlin P, Bundsen P. Pain Relief during delivery by transcutaneous nerve stimulation. Pain 4:59-65, 1977