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Prescribing in pregnancy and breastfeeding

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Synopsis

Assess maternal, fetal and infant medicine risks using gestation, exposure and clinical need, and translate evidence into a practical prescribing and counselling plan.

  • Assess the illness and the medicine together: untreated maternal disease can harm both the pregnant person and the fetus, so an automatic stop is not a complete risk assessment.
  • Record gestational age, exact product, route, dose, timing and duration. Early developmental exposure, later fetal effects and effects near birth are different questions.
  • Use current UKTIS/BUMPS, SPS, relevant NICE guidance and the exact SmPC. A restrictive product statement and specialist clinical guidance may answer different questions; document the reasoning for the actual decision.

Reasoning priorities

01
Gestational dating and exposure timeline

Relate a medicine course to the relevant pregnancy stage.

Use the best available gestational assessment and document uncertainty when dates are unclear. A several-day NSAID course at 25 weeks raises different issues from an isolated preconception dose. Refer targeted fetal monitoring decisions to the appropriate pregnancy or teratology service rather than inventing reassurance from a normal early scan.

Worked reasoning

Worked caseAssess an analgesic request at 25 weeks

A 30-year-old at 25 weeks of pregnancy, weighing 68 kg with normal renal and liver function, requests ibuprofen for a mild headache. Blood pressure is 118/72 mmHg; she has no visual symptoms, fever, neurological features or existing analgesic exposure.

  1. First confirm the supplied absence of warning features and assess whether the headache needs further investigation. The normal pressure is one reassuring input, but persistent, severe or changing symptoms would require reassessment rather than repeated symptomatic treatment.
  2. Identify the requested medicine as a systemic NSAID and place the exposure at 25 weeks. Current MHRA advice is to avoid use from 20 weeks unless clinically necessary; the request therefore needs an alternative analgesic discussion, not an unrestricted over-the-counter recommendation.
  3. For this otherwise suitable adult, choose paracetamol 500 mg to 1 g orally when required, at least 4 hours between doses, with no more than four doses and no more than 4 g in any 24 hours. Advise the lowest effective dose for the shortest needed course and check combination products before supplying it.
  4. Give the final action: use the agreed paracetamol regimen if needed, avoid self-starting ibuprofen and seek assessment if symptoms persist or warning features develop. Verify independently that the total daily paracetamol exposure includes all products and that she can explain the dose spacing and reason for reassessment.

Key medicines

Paracetamol for short-term pain or feverFor a suitable adult weighing at least 50 kg, 500 mg to 1 g orally as needed, at least 4 hours apart, no more than four doses and no more than 4 g in any 24 hours; use the lowest effective dose for the shortest necessary duration.Check all combination products. Lower weight, liver disease, malnutrition or significant renal impairment requires dose or interval review. Persistent pain or fever needs assessment; pregnancy does not justify exceeding the ordinary total dose limit.
Folic acid around conceptionUsually 400 micrograms orally once daily before conception and through the first 12 weeks; selected higher-risk patients require a prescribed 5 mg orally once-daily regimen under current pregnancy guidance.A previous or family neural-tube defect, diabetes or certain medicines may require the higher dose. Confirm the individual criteria rather than equating every supplement or body-weight category with an automatic 5 mg indication.
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Sources and review status10 sources · checked 7 Sept 2026 · clinical review pending
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 7 Sept 2026; clinical approval remains outstanding.

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom