Pain Relief in Labour

Most women do not require pain relief during early labour, but seek it once active phase of 1st stage labour begins. Non-drug techniques can be learnt as part of antenatal care, including relaxation techniques. As pain increases with advancing labour, the woman should be aware that drugs are available and not made to feel that she has failed if she uses them.

Women who receive continuous support during labour are more likely to give birth unaided and less likely to use analgesia. This is more effective when it is started early in labour, by women who are not part of the hospital staff. There is research to support the use of doulas, but equally effective with trusted member of family or friend.

TENS applies controlled mild electrical stimulation to the skin by means of electrodes. Stimulating peripheral nerve endings in this way seems to inhibit the transmission of painful impulses at the dorsal horn of the spinal column, and/or activate some of the descending pain-inhibitory systems above the spine. TENS may also stimulate the body to produce natural endorphins.

• Randomised controlled trials provide no compelling evidence for TENS having any analgesic effect during labour.¹
• However, papers show a high degree of patient satisfaction with this method.² During TENS application pain scores are significantly lower (p< 0.0001), but there is no statistically significant difference in incidence of epidural analgesia in TENS users.

NICE advises that it is NOT offered to women in established labour.³

A recent Cochrane review looked at studies involving acupuncture, acupressure, aromatherapy, hypnosis, massage and relaxation techniques.⁴

• The trials of acupuncture showed a decreased need for pain relief. Women taught self-hypnosis had decreased requirements for pharmacological analgesia including epidural analgesia and were more satisfied with their pain management in labour compared with controls.
• No differences were seen for women receiving aromatherapy.
• Acupuncture and hypnosis may be beneficial for the management of pain during labour; however, the number of women studied has been small.
• Few other complementary therapies have been subjected to proper scientific study.

Immersion in water during labour is claimed to increase maternal relaxation and reduce analgesia requirements. It is supported by the Royal College of Obstetricians for healthy women with uncomplicated pregnancies.⁵ Concerns have been raised however, that there may be greater harm to women and/or their babies e.g a perceived risk associated with neonatal inhalation of water and maternal/neonatal infection.

• A Cochrane review found that water immersion during the first stage of labour reduces the use of analgesia and reported maternal pain, without adverse effects on labour duration, operative delivery or neonatal outcome.⁶

This is a 50:50 mixture inhaled during painful contractions during 1st and 2nd stages of labour. It is often used to supplement to pethidine.

• The main advantages are that it is under the patient's control, it takes effect within seconds and wears off quickly with no side-effects.
• Half of women obtain satisfactory relief.
• It is generally considered safe, but there has been a case report of severe hypoxaemic episodes associated with its use in labour, in an otherwise healthy woman.⁷

Pethidine IM; is widely used. Is effective within 15 minutes and lasts for 2-3 hours. There has been wide debate over the efficacy of pethidine.

• One study found that systemic pethidine was more effective at relieving labour pain than placebo, but its analgesic effect was modest.⁸
• A recent Swedish study showed that opioids did not relieve labour pain, but did reduce anxiety and discomfort.⁹
• Other intramuscular opiates include diamorphine, meptazinol and pentazocine, however there is little evidence to show superiority of one over another.¹⁰

Epidural analgesia is a central nerve block technique achieved by injection of a local anaesthetic close to the nerves that transmit pain. It is widely used as a form of pain relief in labour. It is also the most effective way of relieving pain in labour - providing complete relief in 95% of cases.
It also has the benefit of avoiding need for greater analgesia/general anaesthetic if forceps, vacuum extraction or caesarean section are required.
It is not associated with increase in symptoms related to perineal trauma and pelvic floor muscle weakness.¹²
Disadvantages are:

• Dizziness or shivering may occur.
• It increases length of 2nd stage.³
• There is an increased rate of operative vaginal delivery.¹³ Many delivery units discontinue epidural to reduce operative delivery rate. However, there is insufficient evidence to support this practice.¹⁴ There is evidence that it increases the rate of inadequate pain relief in the second stage of labour.
• Transient hypotension occurs in 20% women.
• Increased numbers of non-reassuring fetal heart tracing on setting up and topping up the epidural - this may be linked to the previous point. This necessitates greater levels of monitoring of mother and child.
• Dural tap in 1% women causing severe headache in 50%.

Epidurals are not available in the community and may steer the woman towards a more interventionalist environment than she wants.

This is a low dose epidural that relieves pain, but allows women to walk about during labour.¹⁵ Staying mobile in the first stage of labour for women with epidural analgesia has not been shown to produce any benefit to delivery outcomes or satisfaction with analgesia, but there are no obvious harms either.¹⁶

The combined spinal-epidural (CSE) technique has been introduced in an attempt to reduce the adverse effects noted with epidural.

• It has been shown to provide a faster onset of effective pain relief from the time of injection, and increase the incidence of maternal satisfaction.¹⁷
• However, CSE women experience more itch.
• There is no difference between CSE and epidural techniques in the incidence of forceps delivery, caesarean section rates or admission of babies to the neonatal unit.

Used for women who have not had an epidural but require forceps or vacuum extraction delivery. It is also used for repair of episiotomy or perineal tear.

• Pudendal nerve block:
  • This uses 10 ml of 0.5% lignocaine injected behind each ischial spine of pelvis via vagina.
  • Use 10 ml for perineal infiltration.
• Perineal nerve infiltration:
  • Inject in fan-like pattern 20 ml of 0.5-1.0% lignocaine from the posterior fourchette at the mid-line in 3 lines.
  • Test before procedure.