Antiphospholipid syndrome (APS)

Antiphospholipid syndrome (APS) is an autoimmune disorder in which the body’s immune system makes antibodies that attack and damage its own tissues or cells.

Normally the immune system makes antibodies to attack infections, but in APS antibodies are made against phospholipids – a type of fat found in many different cells and tissues. It is also known as Hughes Syndrome or sticky blood syndrome.

If you have APS you will have a combination of the following:

  • antiphospholipid antibodies (aPL)
  • blood clots and/or
  • pregnancy problems, including miscarriage or preterm birth.

It is possible to just have antiphospholipid antibodies (aPL) but not to have any symptoms or health problems. In this case you would not be classed as having antiphospholipid syndrome.

In pregnancy, APS is linked to recurrent miscarriage, intrauterine growth restriction, preterm birth and pre-eclampsia. If you have had three or more first trimester miscarriages or one or more second trimester miscarriages it is one of the screening tests you will be offered to look for possible causes because it is one of the most treatable causes of recurrent miscarriage.

With diagnosis and treatment however, the majority of women have a successful pregnancy. 

How does antiphospholipid syndrome affect pregnancy

In early pregnancy the antiphospholipid antibodies (aPL) can cause early miscarriages because they prevent the pregnancy from embedding properly in the womb, and they inhibit the growth of fetal cells.

In later pregnancy the antibodies can cause clots in the placenta, which interferes in the flow of blood and nutrients to the baby.

What does it mean for me and my baby?

If you have already been diagnosed

If you already know you have APS, tell your GP or midwife before you try for a baby, or as soon as you know you are pregnant so you can get the right treatment . The doctor can also make sure your current medication is not harmful to the baby.

Treatment with aspirin and/or heparin is usually started at the beginning of the pregnancy and may continue for one to six weeks after you have given birth. Warfarin isn't recommended during pregnancy because it carries a small risk of causing birth defects.

Treatment is most successful when it begins early (during the attempt to conceive if possible). Although APS cannot be cured, its complications and symptoms, including pregnancy complications, can be reduced and with treatment you are likely to have a healthy baby.

If you have APS you and your baby will be monitored closely throughout your pregnancy for pre-eclampsia and intrauterine growth restriction. The anti-blood-clotting (anti-coagulant) treatment you will receive during pregnancy will be adjusted during or just before labour to prevent heavy blood loss. You and your baby will be monitored very carefully during labour and birth.

If you have not been diagnosed yet

If APS is suspected due to recurrent miscarriage or other symptoms, you will be tested for the syndrome. This will be done with two separate blood tests looking for antibodies at least 6-12 weeks apart.

It is recommended that you do not try to get pregnant until your diagnosis is confirmed as the hormones released by pregnancy interfere with the tests and they will not be conclusive. Waiting until the diagnosis is confirmed also means your treatment can start at the best time – before conception.

After your pregnancy

If APS did not affect you before you became pregnant you may still be monitored and treated for some time after the birth to make sure you continue to be unaffected after pregnancy.

APS is linked to stroke, heart attack and kidney damage, so you will be told to look out for the symptoms of blood clots :

  • balance and mobility problems
  • vision problems, such as double vision
  • speech and memory problems
  • a tingling sensation or pins and needles in your arms or legs
  • fatigue (extreme tiredness)
  • repeated headaches or migraines.

To find out more about Antiphospholipid Syndrome, visit NHS Choices or APS Support UK's website.


  1. Ismail A et al (2013) Role of Antiphospholipid Antibodies in Unexplained Recurrent Abortion and Intrauterine Fetal Death. Life Science Journal, 2013. 10(1).
  2. Keeling D, Mackie I (2012) Guidelines on the Investigation and Management of Antiphospholipid Syndrome. BJH Guideline. Wiley Online Library
  3. RCOG (2011) The Investigation andTreatment of Couples with Recurrent First-trimester and Second-trimester Miscarriage. 2011, Royal College of Obstetricians and Gynaecologists.
  4. James D, Steer P (2011) High risk pregnancy, management options. Fourth edition ed. 2011: Elsevier Saunders.
  5. NHS Choices (accessed Oct 2016) Antiphospholipid syndrome (APS)

  6. Hughes Syndrome Foundation (Accessed Oct 2016) About Hughes Syndrome

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    Last reviewed on October 1st, 2016. Next review date October 1st, 2019.

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    Please note that these comments are monitored but not answered by Tommy’s. Please call your GP or maternity unit if you have concerns about your health or your baby’s health.
    • By Jo (not verified) on 4 Feb 2020 - 17:13

      I had one positive result for anticardiolipin antibodies but have for pregnant before second test to confirm. I went to doctor but he said I don’t need any medicine unless the obstetrician says so but obstetrician hasn’t got in touch yet, should I go back and push for at least aspirin. I’ve had two consecutive miscarriages 11 weeks and 7 weeks. I’m really really anxious and feel like it’s just going to happen again! I am currently 4.4 weeks

    • By Kate Hindle (not verified) on 20 Dec 2017 - 22:39

      Hi there

      Thanks for this great article.

      Please can you note that our charity has changed its name from the Hughes Syndrome Foundation to APS Support UK and our website address is

      Also, can we have permission to link to this article from our website please?

    • By Midwife @Tommys on 4 Jan 2018 - 11:56

      Hi Kate,
      Thank you so much for letting us know that the name of the charity has changed, we will edit this. Absolutely we would love for you to link to any of our information, that would be great.
      Many thanks, Tommy's midwives x

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