Clinical overview
Labour pain is among the most severe pain a woman will experience, yet the right analgesic for any given woman is rarely the strongest one — it is the option that matches her physiology, her parity and stage of labour, her medical and obstetric risk profile, her preferences, and, crucially in South Africa, the level of care and the staff and drugs actually available at the place she is birthing. The FCOG(SA) objective is a selection task: you are not asked merely to list modalities, but to weigh options against indications and complications for the woman in front of you. That is a higher-order skill. A registrar who can recite that epidural is "the most effective" but cannot recognise when it is contraindicated, cannot consent for it honestly, or cannot manage a hypotensive crash or a dural puncture, has not met the objective.
The South African reality frames every decision. The National Integrated Maternal and Perinatal Care Guideline (NDoH, 2024) sets the expectation that pain relief is offered, but regional analgesia (epidural) is largely confined to regional and tertiary hospitals with on-site anaesthetic cover; the typical district clinic or community health centre relies on non-pharmacological support, intramuscular opioids, and inhaled nitrous oxide. Knowing this geography — and knowing when inadequate analgesia is itself a reason to refer up a level of care — is part of selecting appropriately. Respectful, autonomy-preserving care (see Respectful care) means the woman's request for pain relief is a legitimate indication in its own right; she does not have to "earn" analgesia by reaching an arbitrary cervical dilatation.
Core knowledge
The neuroanatomy of labour pain
Pain in the first stage arises from uterine contraction and cervical dilatation. It is visceral, poorly localised, and carried by small afferent C-fibres entering the spinal cord at T10–L1. As labour advances into the second stage, somatic pain from distension of the vagina, pelvic floor and perineum is added, transmitted via the pudendal nerve to S2–S4. This anatomy explains why a low blockade (e.g. a pudendal block) covers perineal but not contraction pain, and why neuraxial techniques must cover from roughly T10 down to the sacral roots to abolish both components.
Untreated severe labour pain is not benign. It drives maternal hyperventilation and a catecholamine surge that can reduce uteroplacental perfusion, and it causes maternal exhaustion and distress. These are physiological arguments for analgesia, but they should be presented carefully rather than overstated — standard teaching, not a hard outcome guarantee.
Figure I15.1 — Labour pain pathways explain why neuraxial blockade covers contraction and perineal pain, while pudendal and local infiltration blocks only cover second-stage or repair pain.
The modalities, in ascending intensity
Non-pharmacological measures — continuous one-to-one support, freedom of movement and upright positions, a warm bath/shower, breathing and relaxation techniques, massage, and a calm environment — reduce reported pain and the need for pharmacological analgesia and have essentially no maternal or fetal harm. They are the universal baseline and should never be skipped because "real" analgesia is available. Continuous labour support is one of the best-evidenced interventions in intrapartum care.
Inhaled nitrous oxide and oxygen (typically a 50:50 premixed gas, "Entonox"/"Entanox") is self-administered, fast on and fast off, with no significant effect on the progress of labour or on the neonate when used appropriately. It gives modest, partial relief. Side-effects are light-headedness, nausea and a dry mouth; adequate room ventilation matters for staff exposure. It is widely usable across levels of care and is a sensible first pharmacological step.
Parenteral opioids — classically intramuscular pethidine (the long-standing workhorse in SA public obstetrics) and, where available, morphine — are cheap, need no anaesthetist, and are deliverable at any level. Their limitations are important and examinable. They provide only partial relief (many women describe sedation and "distance from" the pain rather than abolition of it), cause maternal nausea, vomiting and sedation, and cross the placenta, risking neonatal respiratory depression and sedation, especially if given close to delivery. Pethidine's active metabolite norpethidine accumulates with repeated dosing and can cause neonatal neurobehavioural effects; this is standard pharmacology teaching. Naloxone must be immediately available for the neonate. Avoid giving an opioid when delivery is anticipated within the next short window if it can reasonably be deferred.