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What is thrombocytopenia?
Thrombocytopenia is a condition whereby the number of platelets in your blood is lower than normal. A patient with thrombocytopenia would be described as ‘thrombocytopenic’. Platelets are important in the formation of blood clots. When they become low, this can affect the body’s ability to stop bleeding if it starts, after an injury for example.
What causes thrombocytopenia in pregnancy?
It is normal for some women to have a fall in their platelets during pregnancy from natural processes, especially in the third trimester. This is known as gestational thrombocytopenia, and it is the most common cause of low platelets in pregnancy. Pre-eclampsia also commonly causes thrombocytopenia.
However, some women develop a condition known as ‘immune thrombocytopenic purpura’ (ITP). This is a type of autoimmune condition. This is when the immune system attacks the body’s own tissues. In ITP, the immune system destroys your own platelets. This mainly happens in the spleen, an organ that sits adjacent to your stomach. If you were diagnosed with ITP before you became pregnant, you may find that your platelet count changes in pregnancy. Many women who are known to have ITP before they become pregnant do not require any treatment in pregnancy.
There is no test to prove if someone has ITP, pregnant or not. Consequently, it is difficult to distinguish ITP from other causes of low platelets which are common in pregnancy. Gestational thrombocytopenia typically resolves in the weeks after the pregnancy has ended.
Why does thrombocytopenia in pregnancy need to be monitored?
Many women have no symptoms but are found to have a low platelet count on routine blood tests in pregnancy. Some women may find that they bruise or bleed more easily or have small red or purple marks on their skin (purpura or petechiae). Occasionally, some women experience more significant bleeding.
Thrombocytopenia in pregnancy is not concerning in most cases. It is important to monitor a low platelet count with regular blood tests to assess for any risks and plan accordingly. Patients with thrombocytopenia in pregnancy will have individualised monitoring schedules according to their platelet count and patient individual factors.
What does thrombocytopenia in pregnancy mean for me?
The results of your blood tests will be reviewed and, if required, you will be referred to the Obstetric Haematology clinic run by a consultant obstetrician and consultant haematologist. During your pregnancy, you may be prescribed medications to help increase your platelet count, particularly just prior to birth, although most women will not require this.
It is unlikely that a low platelet count will affect your birth. However, depending on your platelet count, some interventions may not be safe to perform. This becomes more important as you approach the time of your birth. If your count drops too low, it may not be possible for you to have epidural or spinal anaesthesia during labour due to the bleeding risk associated with the procedure.
For some women, we may recommend an appointment with an anaesthetist who would discuss pain relief options in more detail, in addition to the possibility of a general anaesthetic. These decisions will be made based on multiple factors, not solely on the platelet count. Not all women with thrombocytopenia will need to speak with an anaesthetist during their pregnancy.
If you become thrombocytopenic during your pregnancy, there is a risk of thrombocytopenia in subsequent pregnancies.
What does thrombocytopenia in pregnancy mean for my baby?
In the case of gestational thrombocytopenia, your baby should not be affected.
If you have immune thrombocytopenic purpura (ITP), your baby will not inherit this. However, the antibodies that bind to platelets can cross through the placenta from the mother into the baby’s circulation. This can cause the baby to briefly have a low platelet count after they are born; we would not know this until we take a blood sample from the umbilical cord to test for their platelet count. Steps will be taken to avoid interventions which may cause bleeding or trauma to the baby at birth, e.g., ventouse (suction delivery).
After delivery, if your baby’s platelet count is found to be low, they will need to be monitored closely with blood tests until their platelet count increases. It is very unlikely that your baby will need treatment for low platelets.
Will there be any long-term effects as my baby grows up?
With gestational thrombocytopenia and pre-eclampsia, there is no expected effect on their normal growth and development. In the case of ITP, once the antibodies have broken down in your baby’s circulation after a few weeks, they will have a normal platelet count and there will be no expected effect on their normal growth and development.
Contact us
If you have any queries relating to this information, please contact the Haematology (blood) service.
About this information
Service:
Haematology (blood)
Reference:
R/019
Approval date:
1 June 2024
Review date:
1 June 2027
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Important note
This page provides general information only. It is developed by clinical staff and is reviewed regularly every 3 years for accuracy. For personal advice about your health, or if you have any concerns, please speak to your doctor.