🩸 Anaemia in pregnancy is defined as a haemoglobin (Hb) level:
- < 11 g/dL in the first and third trimesters
- < 10.5 g/dL in the second trimester
🤰 It reflects an inability to meet the increased oxygen demands of pregnancy due to reduced red cell mass or haemoglobin concentration.
📉 Pregnancy is associated with a disproportionate increase in plasma volume relative to red cell mass, leading to physiological (dilutional) anaemia, especially mid-pregnancy.

🌍 Epidemiology

📊 Anaemia affects approximately 41.8% of pregnant women globally (WHO).
🌎 Higher prevalence in low- and middle-income countries due to:
- 🍽️ Nutritional deficiency
- 🦠 Parasitic and chronic infections
- 🚫 Limited access to antenatal care
🇬🇧 In the UK, iron deficiency remains the most common cause, particularly in multiparous women and those with dietary restriction.

🧬 Causes

🔩 Iron deficiency anaemia (most common): Increased fetal demand + placental transfer + maternal blood volume expansion.
🧪 Physiological (dilutional) anaemia: Plasma volume ↑ 30–50%, red cell mass ↑ only ~20–30% → Hb falls (not pathological).
🥬 Folate deficiency: Increased cellular turnover and fetal neural tube demands.
🧠 Vitamin B12 deficiency: Malabsorption, vegan diet, pernicious anaemia.
🧬 Haemolytic anaemias: Sickle cell disease, thalassaemia.
🔥 Anaemia of chronic disease: Inflammatory cytokine-mediated iron sequestration.

⚠️ Risk Factors

🥗 Poor dietary intake (iron, folate, B12)
👶 Multiple pregnancy or high parity
⏱️ Short inter-pregnancy interval
🦠 Chronic infection (e.g. HIV, TB, malaria)
🩸 Heavy menstrual bleeding pre-pregnancy
🧬 Pre-existing anaemia or malabsorption (e.g. coeliac disease)

🚨 Complications

🤱 Maternal:
- Preterm labour
- Placental abruption
- Postpartum haemorrhage
- Heart failure (severe anaemia)
- Infection and poor wound healing
👶 Fetal:
- Fetal growth restriction
- Low birth weight
- Preterm birth
- Stillbirth (severe untreated anaemia)
- Impaired neurodevelopment due to chronic hypoxia

🛡️ Prevention

🥩 Encourage iron-rich foods: red meat, poultry, fish, legumes, fortified cereals.
🥬 Ensure adequate folate (leafy greens, citrus) and B12 (meat, dairy, eggs).
💊 Routine supplementation:
- Iron: 30–60 mg daily
- Folic acid: 400 mcg daily (5 mg in high-risk women)
🩺 Hb screening at booking and again at 28 weeks (± later if high risk).

📊 Types of Anaemia in Pregnancy

🧬 Type	🤒 Presentation	🔍 Key Signs	🧪 Investigations	💊 Management
🔩 Iron Deficiency	Fatigue, dyspnoea, palpitations, dizziness	• Pallor (conjunctiva) • Glossitis • Angular stomatitis • Brittle nails • Pica	• ↓ Hb, ↓ MCV • ↓ Ferritin, ↓ serum iron • ↑ TIBC	• Oral iron (ferrous sulphate) • IV iron if severe/intolerant • Iron-rich diet + vitamin C
🥬 Folate Deficiency	Fatigue, irritability, poor concentration	• Pallor • Glossitis • Weight loss • No neurological signs	• ↑ MCV (macrocytosis) • ↓ Serum folate	• Folic acid 400–800 mcg daily • Dietary optimisation
🧠 Vitamin B12 Deficiency	Fatigue + neurological symptoms	• Neuropathy • Ataxia • Loss of vibration sense • Glossitis	• ↑ MCV • ↓ B12 • ↑ MMA & homocysteine	• IM B12 injections • Oral B12 if mild • Dietary correction
🧬 Haemolytic Anaemia	Fatigue, jaundice, dark urine, pain crises	• Jaundice • Splenomegaly • Pain crises (SCD)	• ↑ Reticulocytes • ↑ LDH, bilirubin • Blood film, Hb electrophoresis	• Treat crises • Transfusion if severe • Folic acid + MDT care
🔥 Anaemia of Chronic Disease	Fatigue, reduced exercise tolerance	• Pallor • Signs of underlying disease	• Normal/↑ ferritin • ↓ Iron, ↓ TIBC	• Treat underlying condition • Iron only if coexistent deficiency

📚 Teaching Pearls

🧠 Mild anaemia in mid-pregnancy is often physiological — avoid over-treating.
🔍 Low ferritin confirms iron deficiency even if Hb is borderline.
🧠 Always exclude B12 deficiency before treating macrocytosis with folate alone.
🤝 High-risk pregnancies (SCD, thalassaemia) require early MDT input.
👶 Treating maternal anaemia improves both maternal and fetal outcomes.

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Anaemia (Pregnancy)

📖 Introduction