Analgesia in Pregnancy

Analgesia in pregnancy treats headache, migraine, musculoskeletal pain, pelvic girdle pain, dental pain and chronic pain while avoiding foetal harm from NSAIDs and neonatal effects from opioids. Untreated pain causes poor sleep, low mood and raised blood pressure, so effective analgesia is part of safe care.

Paracetamol. First-line analgesic in all trimesters. Associations with later neurodevelopmental disorders are contested and likely confounded; use the lowest effective dose for the shortest time without withholding it.

NSAIDs. Possible miscarriage association near conception; foetal renal dysfunction and oligohydramnios after 20 weeks; ductus arteriosus constriction from 30 weeks.

Opioids. Short courses are acceptable. Long-term use causes neonatal opioid withdrawal syndrome; codeine and tramadol depend on CYP2D6 and are unpredictable.

Paracetamol. 1 g orally or IV every 4 to 6 hours; maximum 4 g daily. Under 50 kg, or with liver risk factors: 15 mg/kg a dose, maximum 60 mg/kg daily.

NSAIDs (only where clearly needed). Ibuprofen 200 to 400 mg orally every 6 to 8 hours for no more than a few days, before 20 weeks only; maximum 1.2 g daily. Not from 30 weeks.

Low-dose aspirin. 75 to 150 mg daily for pre-eclampsia prevention is not an analgesic regimen and continues to 36 weeks.

Weak opioids. Codeine 30 to 60 mg orally every 4 to 6 hours, maximum 240 mg daily, for no more than 3 days. Tramadol 50 to 100 mg every 4 to 6 hours, maximum 400 mg daily, short courses only.

Strong opioids. Morphine immediate release 5 to 10 mg orally every 4 hours as needed; oxycodone 5 mg every 4 to 6 hours as an alternative. Titrate to effect; give laxatives.

Opioid use disorder. Continue methadone (often 60 to 120 mg daily; requirement rises in the third trimester, and split twice-daily dosing helps) or buprenorphine 8 to 24 mg daily. Do not detoxify in pregnancy.

Migraine, acute. Paracetamol 1 g with metoclopramide 10 mg; sumatriptan 50 to 100 mg orally, repeat after 2 hours if needed, maximum 300 mg daily (or 6 mg subcutaneously, maximum 12 mg daily). Prednisolone short course for status migrainosus after specialist review.

Migraine, prevention. Propranolol 40 mg 2 to 3 times daily (80 to 160 mg daily) or amitriptyline 10 to 25 mg at night, up to 50 mg. Avoid valproate and topiramate.

Neuropathic pain. Amitriptyline 10 mg at night, up to 50 mg. Gabapentin 300 mg at night, titrated to 900 to 1800 mg daily, if amitriptyline fails; pregabalin has a small malformation signal and less data.

Local and regional. Lidocaine and other local anaesthetics for dental work and minor procedures at usual doses (maximum lidocaine 3 mg/kg, or 7 mg/kg with adrenaline).

Avoid. NSAIDs from 30 weeks and preferably from 20 weeks; COX-2 inhibitors; high-dose aspirin; valproate and topiramate for migraine; ergotamine (uterotonic); codeine in known ultra-rapid metabolisers.

Opioid hazards. Constipation (worse in pregnancy), nausea, sedation, maternal respiratory depression with sedatives. Neonatal opioid withdrawal after more than about 2 to 3 weeks of regular use near term: alert the neonatal team.

Interactions. Opioids with benzodiazepines, gabapentinoids or alcohol: respiratory depression. Tramadol and triptans with SSRIs or SNRIs: serotonin toxicity (rare). Methadone with rifampicin or efavirenz: falling methadone levels and withdrawal.

Special groups.

• Kidney impairment: avoid NSAIDs; reduce gabapentin; avoid morphine accumulation by lowering dose or using oxycodone.
• Liver impairment: paracetamol maximum 2 to 3 g daily; reduce opioid doses.
• Breastfeeding: paracetamol, ibuprofen and short-course morphine are compatible; avoid codeine and tramadol.
• Regional: ask about over-the-counter diclofenac and herbal analgesics, both commonly used in East Africa.

Monitoring. Liquor volume and ductus assessment if an NSAID was taken after 20 weeks for more than 48 hours. Sedation and respiratory rate after opioid dose increases. Bowel habit on any opioid.

Red flags in headache. New severe headache after 20 weeks needs blood pressure and urine protein checks for pre-eclampsia; sudden, thunderclap or positional headache, or neurological signs, need urgent imaging for haemorrhage, venous sinus thrombosis or other causes.

Stopping rules. Stop NSAIDs if oligohydramnios or ductal constriction is found. Taper opioids used for more than 2 weeks by 10 to 25% every few days rather than stopping abruptly, except in opioid substitution therapy, which continues.

Referral and escalation. Refer to pain or addiction services for chronic opioid use, opioid use disorder or uncontrolled pain; inform the neonatal team before birth when opioids, gabapentinoids or benzodiazepines are used near term.