Anaemia in Pregnancy

Risk Factors

The risk factors for developing anaemia during pregnancy include:

• Haemoglobinopathies
  • Thalassaemia
  • Sickle cell disease
• Increasing maternal age
• Low socioeconomic status
• Poor diet
• Anaemia during previous pregnancy

Clinical Features

Common symptoms of anaemia include dizziness, fatigue and dyspnoea. However, it should be noted that these are also all features of a normal pregnancy. Anaemia can be asymptomatic, and may only be detected on a full blood count.

On examination, the patient may have pallor (best identified in the mucosa of the tongue and mouth). Less common features include koilonychia (spoon-shaped nails) and angular cheilitis (ulceration at the corners of the mouth).

By CHeitz [CC-BY-2.0], via Flickr

Fig 1
Koilonychia (spoon-shaped nails), a rare sign of anaemia.

Differential Diagnosis

Anaemia has a wide variety of possible causes. The differential diagnoses can be categorised by the mean corpuscular volume (MCV):

Table 1 – The differential diagnoses for anaemia. Note that the cut-offs for MCV will vary between different laboratories.

Investigations

The principle investigation in anaemia is a full blood count, assessing the haemoglobin level and mean corpuscular volume.

By OpenStax College [CC BY 3.0], via Wikimedia Commons

Fig 2
Coloured scanning electron micrograph, showing a sickled red blood cell.

Serum ferritin is not routinely measured – even in cases where iron deficiency anaemia is suspected. One exception to this is in areas with a high prevalence of haemoglobinopathies.

Haemoglobinopathy screening should be considered in patients with confirmed anaemia and an unknown haemoglobinopathy status.

Further investigations are dependent on the suspected cause:

• Folate deficiency– serum folate (<7 nmol/L indicates deficiency – although this may vary between different laboratories).
• Beta thalassaemia– haemoglobin electrophoresis (HbA2 >3.5% is diagnostic).
• Sickle cell disease– haemoglobin electrophoresis (HbA is absent, 80-95% HbSS and 2-20% HbF).

Management

Iron Deficiency Anaemia

If the anaemia is micro- or normocytic, then the most likely cause is iron deficiency. In these women, a trial of oral iron (100-200mg) should be considered as first line management, and as a diagnostic test. A full blood count should be repeated after two weeks of treatment, examining for an increase in haemoglobin.

A parental iron infusion (Ferinject®) should be considered if compliance is poor or there is evidence of malabsorption.

Table 2 – Amount of elemental iron in common preparations

Other Causes

Management of other types of anaemia in pregnancy is dependent on the underlying cause:

• Folate deficiency– folate supplementation; usually 5mg folic acid once daily. This can be increased up to three times a day if required.
• Beta thalassaemia– folate supplementation and blood transfusions as required; aiming for a Hb of 80g/L during pregnancy, and 100g/L at delivery (depending on symptoms).
• Sickle cell disease– folate supplementation and iron supplementation if there is laboratory evidence of iron deficiency.