Anaemia is a condition in which you don't have enough red cells in your blood. Red blood cells contain haemoglobin, which carries oxygen from your lungs to the rest of your body. If your haemoglobin levels are very low, your body tissues won’t be getting enough oxygen.

During pregnancy, the number of red blood cells you have increases, but so does the amount of the plasma (liquid) in which the blood cells are carried. This means that your blood is more dilute, and your haemoglobin levels slightly lower, than usual. Levels as low as 10 g/dl are normal and are generally no cause for concern or treatment - provided you are otherwise well.

A few women do become truly anaemic in pregnancy. If this happens, you may feel very tired and may look pale. You may be short of breath and may suffer from dizzy spells. Severe anaemia can undermine your general health and lower your ability to cope with infection. Anaemia can also make you feel miserable and anxious.

You will be offered a blood test for anaemia at your first antenatal appointment. Further checks will be offered later in pregnancy. Low haemoglobin levels without any other signs of iron deficiency don’t usually require any treatment. If, however, the tests show that you are anaemic, your doctor or midwife may prescribe iron tablets. The level at which iron tablets may be recommended varies from place to place. Generally, if your haemoglobin falls below 10 (or maybe 10.5g d/l) you will be offered iron tablets.

Don't worry if you are not routinely given iron tablets during pregnancy. Unless they are really needed by the body, iron tablets can cause more problems than they solve.

Iron tablets can sometimes cause constipation or stomach pains. If you find that they do this for you, ask your midwife or doctor whether the drug is still necessary. If it is, ask for an alternative prescription; there are lots to choose from!