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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Anaemia and thrombocytopenia in pregnancy

Obstetrics and gynaecology · UK scope · Sources checked 7 Sept 2026 · Clinical review pending

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Cytopenia with bleeding or organ dysfunction

Anaemia or thrombocytopenia accompanied by haemodynamic instability, active bleeding, hypertension, upper abdominal pain, neurological signs or haemolysis may indicate haemorrhage, HELLP or thrombotic microangiopathy.

Action: Arrange urgent maternity and haematology assessment, assess circulation and bleeding, repeat the blood count with film, and request renal, liver, haemolysis and coagulation studies while treating the suspected emergency.

Synopsis

Distinguish physiological blood-count changes from iron deficiency, immune thrombocytopenia and obstetric emergencies, and plan investigation, treatment and delivery-related safety.

  • Pregnancy expands plasma volume more than red-cell mass, but haemodilution must not be assumed to explain every low haemoglobin.
  • UK BSH thresholds define anaemia as haemoglobin below 110 g/L in the first trimester, below 105 g/L in later pregnancy and below 100 g/L postpartum.
  • Ferritin below 30 micrograms/L supports iron deficiency; inflammation can conceal depleted stores behind a normal or elevated result.
  • Treat established iron deficiency with a tolerable oral elemental iron dose and check the haemoglobin response after about two to three weeks.
  • Gestational thrombocytopenia is usually mild, isolated and late, with no bleeding or systemic illness and postpartum resolution.
  • Platelet timing, trend, film and accompanying features determine the differential and urgency more reliably than a single number.

Key red flags

Bleeding with cardiovascular compromise, chest pain, syncope or severe breathlessness requires emergency assessment rather than an outpatient iron prescription.

A rapidly falling platelet count with hypertension, epigastric pain, renal impairment or neurological symptoms requires urgent exclusion of HELLP and thrombotic microangiopathy.

Very low platelets, spontaneous mucosal bleeding or a new additional cytopenia needs prompt haematology involvement regardless of gestation.

Investigation priorities

01
Full blood count with prior-result comparisonFirst step

Characterise haemoglobin, indices, platelets and whether more than one cell line is affected.

Management branches

Iron replacementTreat confirmed or strongly suspected iron deficiency

Anaemia and clinical or laboratory findings support depleted iron stores without immediate instability.

  1. Offer 40–80 mg elemental oral iron daily using a preparation and schedule the patient can tolerate, with explanation of gastrointestinal effects.
  2. Separate iron from interacting medicines and foods where practical, and arrange a haemoglobin check after roughly two to three weeks.
  3. If response is poor, assess adherence and cause; consider specialist intravenous iron after the first trimester when oral treatment is ineffective, intolerable or too slow.

Key medicines

Ferrous sulfateOne ferrous sulfate 200 mg tablet orally once daily provides approximately 65 mg elemental iron; review response after two to three weeks and continue replacement for three months after haemoglobin normalises and at least six weeks postpartum.Explain nausea, constipation and dark stools; separate from levothyroxine and other interacting drugs, and keep securely away from children.
Intravenous ironAfter the first trimester, calculate replacement from body weight, haemoglobin deficit and the chosen product’s maximum single and weekly doses; administer in a monitored service with resuscitation facilities.Confirm deficiency first; infusion reactions and product-specific hypophosphataemia risk require counselling, and active infection or alternative anaemia may alter suitability.
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Sources and review status5 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.

  • BSH UK iron deficiency in pregnancy guideline
  • BSH iron deficiency pregnancy guideline landing page
  • NHS Greater Glasgow thrombocytopenia in pregnancy
  • NICE NG133 hypertensive pregnancy disease
  • NICE NG201 antenatal screening recommendations

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom