Causes of Anaemia in Pregnancy

There are several complications that can show up during pregnancy. One of such complications that can develop during pregnancy is anaemia. The definition of anaemia in pregnancy is not the same as what may be considered as anaemia in a non pregnant woman.

Anaemia in pregnancy is generally defined as haemoglobin levels < 10g/dL or hematocrit level < 30%. Haemoglobin is a protein on the red blood cell that is responsible for carrying oxygen from lungs to other tissues in the body. Haemoglobin levels < 12g/dL in non pregnant women is considered as anaemic. The hematocrit is the measure of the percentage of red blood cells in a given volume of blood sample.

Anaemia in pregnancy have also been defined as haemoglobin levels < 11g/dL in first trimester, < 10.5g/dL in second trimester and < 11g/dL in third trimester. Normally during pregnancy, erythroid hyperplasia of the bone marrow occurs and red blood cells increases, however there is a disproportionate increase in plasma volume which results in hemodilution. It is this hemodilution that makes hematocrit levels from 38% – 45% in a healthy non pregnant woman to 34% during normal pregnancy and 30% in late pregnancy.

what are the causes of anaemia in pregnancy? 

  • Physiological causes as a result of blood volume expansion
  • Pathological causes of anaemia from hemolytic disorders like sickle cell disease, malaria, G6PD, thalasemia, helminthiasis, and schistosoma infection. Chronic illness like Tuberculosis and HIV as well as blood loss from injuries, menorrhagia and gastrointestinal bleeding can cause anaemia.
  • Nutritional causes include iron deficiency, folate deficiency and vitamin B12 deficiency.
  • Drug induced anaemia.
  • Bone marrow failure.

Nutritional causes accounts for the highest occurrence of all cases of anaemia in pregnancy. Iron deficiency anaemia is the most common cause of anaemia in pregnancy accounting for about 75% to 95% of all cases of nutritional causes of anaemia in pregnancy. A pregnant woman often has insufficient iron stores to meet the demands of pregnancy. Iron is one of the components needed to produce haemoglobin in the body.

Folate is needed for nucleic acid formation and useful in reducing the risk of neural tube defect in fetus. The body needs folate and vitamin B12 to produce new red blood cells and any anaemia resulting from insufficiency of folate and vitamin B12 is termed folate or folic acid deficiency anaemia and vitamin B12 deficiency or megaloblastic anaemia respectively.

what are the risk factors for anaemia in pregnancy? 

The predisposing factors for anaemia to develop during pregnancy include the following :

  • Multiple gestation (twin pregnancy or more)
  • Poorly spaced consecutive pregnancies
  • Severe vomiting from morning sickness
  • Pregnant teenager
  • Previous history of anaemia in pregnancy
  • Do not eat foods rich in iron and vitamins.

Symptoms of anaemia in pregnancy 

Anaemia in pregnancy can be asymptomatic especially early in pregnancy due to other changes occurring which may have similar symptoms. However when anaemia is severe enough, possible symptoms that can be noticed include

  • Fatigue
  • Headache
  • Dizziness
  • Shortness of breath
  • Rapid breathing
  • Difficulty concentrating
  • Pale skin, lips, nail, conjunctiva and mouth mucosa are signs of anaemia that can be picked during examination.

How anaemia is diagnosed in pregnancy 

Diagnosis of anaemia in pregnancy involves consideration of the presenting clinical features (signs and symptoms) which may suggest anaemia. To confirm the diagnosis of anaemia in pregnancy requires laboratory investigations which include

  • Haemoglobin level test
  • Hematocrit test
  • Mean Corpuscular Volume (MCV) to determine the type of anaemia.
  • Serum iron levels
  • Iron binding capacity test
  • Serum folate and vitamin B12 level.

Management of anaemia in pregnancy 


Advice on diet is important in the management of anaemia in pregnancy. The patient should increase green leafy vegetables in her diet which are rich in iron and also increase animal foods like meat, eggs and diary products to improve folate and vitamins.

Supplements are used to help correct nutritional causes of anaemia in pregnancy. Supplements of iron, folic acid and vitamin B12 are available and are given as routine drugs during antenatal care.

Other pathological causes of anaemia are to be treated accordingly and haemoglobin levels < 7g/dL require blood transfusion and/or fluid resuscitation.

Complications of anaemia in pregnancy 

  • Preterm delivery
  • Perinatal mortality
  • Postpartum depression
  • Blood transfusion
  • Fetal anaemia
  • Child with developmental delay
  • Neural tube defects (spina bifida)

How to prevent anaemia in pregnancy 

Three important measures to take to avoid anaemia in pregnancy are:

  1. Routine antenatal visits for routine check up and supplementation.
  2. Nutritional improvements for iron and vitamin rich sources of food.
  3. Prevention of malaria and other pathological causes of anaemia with adequate management if they occur.




Medscape : “Anaemia and thrombocytopenia in pregnancy” : “Anaemia in pregnancy ” : “Anaemia in pregnancy ”



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