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Anaemia in Pregnancy

Anaemia in Pregnancy

Red blood cells carry oxygen around the human body.

Red blood cells are produced in bone marrow. Within each red blood cell is a protein known as haemoglobin. Its function is to carry oxygen absorbed by the lungs to organs and cells throughout the body.

The ability of the body to produce haemoglobin is dependent on adequate supplies of iron, vitamin B12 and folate.

Oxygen is released by the red blood cells and is used by the body’s tissues to break down the necessary sugars and fats that are used as the body’s fuel.

Once this fuel is used up it produces a waste product called carbon dioxide; which in turn binds to the red blood cells and is removed by the lungs.

What is anaemia?

Anaemia occurs when there is a decrease in haemoglobin and red blood cells being produced.

A person with anaemia will have less oxygen being delivered to their body. As a result they will feel as though they constantly running out of oxygen, much like you feel when you have gone for a fast run. They will have some of the following symptoms:

  • Lethargy
  • Tiredness
  • Weakness
  • Breathlessness
  • A drop in blood pressure when they stand, so they become dizzy
  • A fast heart rate known as palpitations
  • Difficulty concentrating
  • Irritability
  • Loss of appetite
  • In severe cases chest pain or headaches

Why do pregnant women become anaemic?

Human blood contains plasma and blood cells. Plasma is the liquid component of blood that helps transport red blood cells to vital organs. It is mostly made of water. When not pregnant the amount of plasma in blood is 2.5 litres. This increases in pregnancy by over 50% so that by 34 weeks there is 3.9 litres of plasma. As a result the concentration of red blood cells and haemoglobin decreases making pregnant women anaemic. This is known as physiological anaemia.

The bone marrow responds by increasing the production of red blood cells by 20-30%; slightly improving the concentration of red blood cells. This increased production is dependent on pregnant women taking iron supplements throughout pregnancy.  

In addition there are other reasons women become anaemic in pregnancy. These include:

  • Dietary: low iron, vitamin B12 and folate intake
  • Malabsorption: the body is unable to absorb nutrients eg in Coeliac Disease
  • Loss of blood: disease that cause blood loss eg from haemorrhoids or stomach ulcers
  • Decreased bone marrow production: infection or cancer
  • Inherited disorders: such as thalassaemia and sickle cell

What tests will show you have anaemia?

At the commencement of pregnancy and again in the second trimester a full blood examination is done. This tests the concentration of haemoglobin in the blood and the size, shape and number of red blood cells. Any abnormality of these tests will direct me towards other tests.

These tests include:

  • Iron levels
  • Vitamin B12 and folate levels
  • Genetic tests for inherited disorders such as a thalassaemia screen

What happens if a pregnant woman is anaemic?

Anaemia in pregnancy will result in symptoms of anaemia; making the experience of pregnancy less pleasant.

Direct effects on the developing baby included a reduced amount of amniotic fluid around baby and the heart rate of the baby being abnormal during child birth.(1) There is also an increased chance of miscarriage, the baby being delivered too early or having a low birth weight(2). Babies born from anaemic mother may also be anaemic and hence have the same symptoms as their mothers.

If a woman is anaemic throughout pregnancy and loses blood during the birth of her child she is at risk of very severe anaemia requiring a blood transfusion or other life saving measures.

How can anaemia in pregnancy be avoided?

It is important for a woman contemplating pregnancy to see her local doctor to have a check up.   At this time advice on anaemia and other conditions can be asked.

Maintaining a balanced diet will provide the necessary nutrients required in pregnancy such as vitamin B12. Green leafy vegetables beans, muesli, broccoli, beef, Brussels sprouts and asparagus contain high levels of folate. Sources of iron can be found in meats, iron fortified breads and cereals, eggs, spinach and dried fruit.

Iron is important for increasing haemoglobin and red cells. It is also required for the development of the baby and the placenta. The daily dose of iron in pregnancy is 30mg/day. To assist in the daily intake it is best to take a pregnancy vitamin that can be obtained from your local pharmacy. Some oral forms of medication may produce gastric upset. Pregnant women should speak to their doctor prior to commencing iron or if they have any side effects from the medication.

Pregnant women are advised to take a folic acid one month prior to pregnancy and to continue this for at least the first three months. Whilst this will prevent anaemia it will also decrease the risk of neural tube defects such as spina bifida. Supplements containing 500mcg of folic acid can be obtained at local pharmacies. Women who have diabetes, epilepsy, are overweight or have had a child with a neural tube defect may require increased doses of folic acid. Pregnant women should consult their doctor regarding their specific requirements.

Balanced vegetarian diets do not have any significant health effects on pregnancy or babies. As these diets vary considerably it is best vegetarians seek advice from a doctor or dietitian to ensure that their diet provides the optimal amount of nutrients required for a successful pregnancy. (3)

 

 

 

 

  1. Carles G, Tobal N, Raynal P, et al. Doppler assessment of the fetal cerebral hemodynamic response to moderate or severe maternal anemia. Am J Obstet Gynecol 2003; 188:794.
  2. Sifakis S, Pharmakides G. Anemia in pregnancy. Ann N Y Acad Sci 2000; 900:125.
  3. Haddad EH, Tanzman JS. What do vegetarians in the United States eat? Am J Clin Nutr 2003; 78:626S