Anaemia in pregnancy

Definition

• Anaemia in pregnancy is a reduced haemoglobin concentration with trimester-dependent cut-offs; according to ACOG these are 11.0 g/dl in the first and third and 10.5 g/dl in the second trimester.

Occurrence & epidemiology

Epidemiology

• According to WHO estimates, about 37% of pregnant women worldwide are anaemic.

Aetiopathogenesis

Aetiology and pathogenesis

• From about 6 weeks, plasma volume increases disproportionately to red cell mass and at its peak is 40–50% above baseline, so that haemoglobin concentration falls by dilution.
• Among pathological causes, iron deficiency anaemia is the most common, particularly in high-income countries.
• Further causes include folate or vitamin B12 deficiency, infections such as malaria, chronic diseases and inherited red-cell disorders such as thalassaemia.

Clinical features

Clinical features and complications

• Common non-specific symptoms are tiredness, dizziness, headache and exertional breathlessness; severe anaemia can cause pale mucous membranes and rapid breathing and heart rate.
• Severe maternal iron deficiency appears to increase the risk of preterm birth, low birthweight and infant death.

Diagnosis

• Iron deficiency is usually defined clinically by a low serum ferritin or reduced transferrin saturation.
• A low ferritin always indicates iron deficiency; however, as an acute-phase reactant, ferritin may be normal despite iron deficiency in infection or inflammation.
• As iron deficiency progresses, first the MCV and then the MCHC fall, producing the typical microcytic hypochromic picture.

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Further reading (selection)

1. Nutrients 2020: Iron Deficiency and Iron Deficiency Anemia: Implications and Impact in Pregnancy, Fetal Development, and Early Childhood Parameters (PubMed Central)
2. WHO fact sheet: Anaemia

Cross-references