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Anaemia in pregnancy 

Anaemia in pregnancy
Anaemia in pregnancy

Sambit Mukhopadhyay

, Edward Morris

, and Sabaratnam Arulkumaran

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date: 26 February 2020

Key learning points

  • Physiology of haematological changes in pregnancy

  • Antenatal management of severe anaemia

  • Careful peripartum management to reduce risk of haemorrhage.


  • Physiological relative reduction in Hb concentration and haematocrit in pregnancy

  • Increase in plasma volume is relatively greater than of red cell mass (physiological anaemia)

  • Effect increases with advancing gestation

  • BUT pathological anaemia should not be overlooked. Significant anaemia (Hb <10.5 g/dL), particularly at booking, is less likely to be physiological, and other causes should be sought

  • Erythrocyte size should be checked

  • Haemoglobinopathies should be excluded, particularly in ethnically susceptible women (assessed as part of the screening tests taken at booking)

  • Thalassaemia/sickle cell disease should be managed jointly with a haematologist and offered prenatal diagnostic testing

  • In the absence of haemoglobinopathies, B12 and folate deficiencies should be excluded and iron deficiency assessed

  • Chronic disease or malnutrition (particularly with coexisting hyperemesis gravidarum) may lead to an iron deficiency

  • Treat anaemia in pregnancy—it is associated with an increase in adverse obstetric events, including PPH and infection. Effective antenatal treatment also reduces the need for peripartum blood transfusion.

Antenatal management

  • Pregnant women obtain virtually all necessary vitamins and minerals from a healthy, balanced diet—except folic acid (in the first trimester, reducing the risk of NTDs) and, for some, iron. It is not clear why some women develop iron deficiency, even with good diet

  • The mainstay of treatment of iron deficiency is supplemental iron. Oral iron can be unpleasant to take, with GI side effects (related to dose)—try different formulations such as syrups (iron is toxic in overdosage)

  • It can take weeks or months to correct iron deficiency; therefore, treatment should be started as soon as the diagnosis is made

  • Appropriate iron supplementation reduces the incidence of anaemia in pregnancy by about 40%

  • Parenteral irons (usually IV sucrose or dextran, or occasionally IM) are effective when oral preparations are not tolerated (British National Formulary (BNF) advises facilities for cardiopulmonary resuscitation (CPR) should be available when giving IV treatment—small incidence of anaphylaxis).

Peripartum management

  • Women giving birth with significant iron-deficient anaemia are at increased risk of adverse obstetric outcomes

  • Women with severe anaemia in the third trimester may benefit from blood transfusion before birth to improve haematocrit rapidly

  • IV access and crossmatching in labour are advisable

  • There is little evidence to determine the safety of erythropoietin in pregnancy, and it is rarely used at present

  • Some women find blood transfusion unacceptable for religious or other reasons. This can pose ethical and legal challenges for obstetricians, particularly in life-threatening situations. These women should be counselled antenatally and have individualized care plans to deal with anaemia and to agree treatment in the event of major haemorrhage.

Further reading

British Medical Association; Royal Pharmaceutical Society (2011). British National Formulary. Issue 62, September 2011. BMJ Group and Pharmaceutical Press, London.Find this resource:

Dodd JM, Dare MR, Middleton P (2004). Treatment for women with postpartum iron deficiency anaemia. Cochrane Database of Systematic Reviews, 4, CD004222.Find this resource:

Reveiz L, Gyte GML, Cuervo LG, Casasbuenas A (2011). Treatments for iron-deficiency anaemia in pregnancy. Cochrane Database of Systematic Reviews, 10, CD003094.Find this resource: