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APS is usually associated with recurrent miscarriage, but it can also cause other pregnancy complications.

Recurrent miscarriage means having three or more miscarriages in a row, and it affects about one in every hundred couples trying for a baby. At least 15% of recurrent miscarriages occur as a result of APS, and it is now recognised as the most common, treatable cause. With correct diagnosis and treatment, the pregnancy success rate has risen from 20% before 1990 to around 70-80% today.

As APS pregnancies are classed as high risk, it is best to try and find a specialised or early pregnancy unit where doctors have prior clinical experience.

Treatment will depend on individual medical history, test results and current circumstances. Generally, if a woman is diagnosed with APS following recurrent miscarriages, she will be treated daily with low dose aspirin (75mg-150mg). It is also common to combine this treatment with daily heparin injections, particularly if a miscarriage has happened in the mid or late trimesters, or if there have been previous pregnancy complications such as pre-eclampsia. The final decision on how best to treat this aspect of APS should be taken after discussion with a specialist in this area.

If a woman has been diagnosed with APS prior to becoming pregnant and is already being treated with warfarin, she will have to change over to daily heparin injections, ideally before the embryo is six weeks old, as warfarin is potentially harmful to the baby.

Some women with APS can have successful pregnancies without any treatment – the reasons for this are still not clear – but pregnancy loss and/or complications are often the first and, in some cases, the only sign of the condition in women and it is then known as Obstetric APS - OAPS.

Pregnancies can be affected in a number of ways:

Early pregnancy loss

The majority of miscarriages in women with APS occur at the early stages of pregnancy in the first 13 weeks.

Late pregnancy loss

Losing a baby in the second and third trimesters (from 14 weeks until birth) is rare in most pregnancies, but is very strongly associated with APS, with a number of losses occurring between three and six months.


Pre-eclampsia affects up to 10% of all pregnancies, but it is twice as likely to occur in women with APS, begins at an earlier stage and is more severe.

Intrauterine growth restriction

Intrauterine growth restriction (IUGR) refers to the reduced growth of a baby while in the womb. It is estimated to affect between 10-30% of babies born to mothers with APS.

In the management of pregnancy in APS, Doppler ultrasound scans will be carried out to discover if there is a fall in foetal blood supply. If there is a problem, the scan can help the specialists decide whether to move towards an earlier (possibly Caeserean) delivery.

Support for the future

As it is not currently possible to identify which women have OAPS as opposed to thrombotic APS, any woman who has been diagnosed is potentially at increased risk from blood clots and should be advised to continue taking 75mg aspirin daily as a precaution. Long term research is being carried out looking into this, but it will be some years before the results are available.

It can be devastating to miscarry one baby after another, and the experience can place enormous strain on you and your partner. The Miscarriage Association's website: www.miscarriageassociation.org.uk/ provides a wealth of information on coping strategies, leaflets and helplines all designed to support your grieving process. Similarly, losing a baby later on in pregnancy can be shattering - SANDS, the Stillbirth and Neonatal Death charity provides support and information to anyone affected by this tragedy.

© 2018 APS Support UK (trading name of the Hughes Syndrome Foundation). Registered Charity Number 1138116. A company limited by guarantee registered in England 7268671.