Pre-existing Diseases in Pregnancy

Long-term pre-existing diseases that could affect the progress of pregnancy or the health of the fetus

  • More common over the age of 35
  • Genetics and lifestyle are not significant factors

If a woman who becomes pregnant has a long-term medical condition, she may need specialist care throughout pregnancy and labour. Pre-existing disorders that could adversely affect pregnancy or the health of the fetus are more common in women over the age of 35. For example, such women are more likely to have pre-existing disorders, such as noncancerous tumours in the uterus (see Fibroids) or diabetes mellitus, which may affect the progress of the pregnancy and the development of the fetus.

Long-term pre-existing disorders and their treatment may affect the progress of the pregnancy. For example, women who have diabetes mellitus are more prone to problems such as high blood pressure (see Hypertension) or premature labour, particularly if the condition is not well controlled. Changes in hormone levels during pregnancy can have adverse effects on diabetes mellitus, which often worsens. However, in some women who have mild asthma, symptoms improve during pregnancy.

The fetus may also be affected by pre-existing diseases in the mother. Some maternal disorders, such as chronic high blood pressure and kidney failure, may affect the function of the placenta and lead to malnourishment of the fetus, affecting its development and growth. For example, a mother who has high blood pressure is at an increased risk of having a smaller than average baby (see Intra-uterine growth retardation). A baby who is born to a mother with diabetes mellitus may have low blood sugar levels immediately after birth.

If you have a long-term pre-existing condition, and are planning to start a family, you should consult your doctor before becoming pregnant. Your condition, and that of your fetus, will need careful monitoring throughout the term of your pregnancy. Your doctor will work with your obstetrician to make sure that you remain as healthy as possible and that the progress of your pregnancy is successful.

What might be done?

If you have a long-term disorder, your doctor will review your condition carefully before you become pregnant to make sure that it is as well controlled as possible.

Your usual treatment may need to be altered while you are pregnant because some drugs can affect the fetus. For example, if you normally take tablets to control your diabetes mellitus, you will have to change to insulin injections (see Drugs for diabetes mellitus). The dose of some treatments may need to be altered, and additional measures may be required to control the pre-existing disorder. For example, women who have epilepsy, and who are taking anticonvulsant drugs to prevent any seizures, will usually be prescribed a higher than normal dose of folic acid in order to reduce the risk of their medication causing neural tube defects, abnormalities of the brain and spinal cord which may occur during pregnancy, in the fetus.

You may have antenatal checkups at more frequent intervals than usual, and your doctor may refer you to an obstetrician specializing in your condition. You may be required to have additional tests, including extra ultrasound scans (see Ultrasound scanning in pregnancy). Additional monitoring may be necessary during labour, and after the delivery your baby may be given a series of tests to ensure that he or she is healthy.

What is the prognosis?

With regular monitoring and carefully adjusted treatment, both before and during a pregnancy, as well as during the birth, pre-existing conditions can be controlled, and they usually carry little risk for either the mother or the fetus. Any changes in the mother’s condition that may have developed as a result of the pregnancy will normally be reversed soon after the baby has been born.

Test: Antenatal Genetic Tests

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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