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Antiphospholipid Syndrome and Recurrent Miscarriages


Updated June 10, 2014

Blood Clots and Recurrent Miscarriage

Tendency to form blood clots, such as from antiphospholipid syndrome, can increase the odds of miscarriage for some women.

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Antiphospholipid syndrome means that a person’s blood contains antibodies against specific types of phospholipids. If you haven’t taken a recent course in college biology (and most of us haven’t), phospholipids are a normal and necessary component in human cells and cells of most other living creatures.

Why Antiphospholipid Syndrome Matters:

When a person has antibodies against phospholipids, this can cause tiny clots in the person’s blood and increase the tendency toward medically important blood clots, such as deep vein thrombosis. Antiphospholipid syndrome increases the risk of many different health problems, ranging from stroke to cardiovascular issues.

Antiphospholipid syndrome can be caused by an autoimmune disease, such as lupus, or it can be a primary condition without any known autoimmune disease.


About 2% to 4% of the general population has antiphospholipid antibodies, and over half of those have primary antiphospholipid antibody syndrome. Antiphospholipid syndrome is a factor in about 15% of women who have recurrent miscarriages. About 10% of people who are diagnosed with antiphospholipid syndrome will ultimately be diagnosed with an autoimmune disease.

Relationship to Recurrent Miscarriages:

Researchers have found that having antiphospholipid syndrome can increase women's chances of recurrent miscarriages. The reason for this is unclear; some researchers believe that antiphospholipid syndrome causes tiny blood clots to block the blood supply to the placenta. Others believe that having antiphospholipid syndrome may interfere with the fertilized egg’s ability to implant in the lining of the uterus.

Antiphospholipid syndrome is well established as a cause of later miscarriages but doctors are still unsure of the role that antiphospholipid antibodies might play in early miscarriage.


Most people who have antiphospholipid antibodies have no symptoms, although though the disorder can cause blood clots and other health problems in some people. For women, recurrent miscarriages may be the only symptom of the disorder.

How Doctors Diagnose Antiphospholipid Syndrome:

Diagnosing antiphospholipid syndrome can be a challenge; the standard tests for lupus anticoagulant antibodies can be unreliable and the sensitivity can vary based on the agent used in each individual laboratory. Generally, when considering antiphospholipid syndrome as a possible factor in recurrent miscarriages, doctors look for a person to be positive for lupus anticoagulant antibodies or anticardiolipin antibodies on more than one occasion before making a diagnosis. Note that having a positive test for lupus anticoagulant antibodies does not mean that a person has the disorder lupus.

Treatment and Prognosis:

Women who have been diagnosed with antiphospholipid syndrome have about a 70% chance for a successful pregnancy with treatment, which usually consists of low-dose aspirin and/or heparin injections. Although this treatment improves pregnancy outcomes for women with antiphospholipid syndrome, these therapies can increase the rates of third-trimester pregnancy complications, however, so women with antiphospholipid syndrome usually need to see a high-risk specialist and have regular prenatal care during pregnancy.

Because antiphospholipid syndrome can be associated with other health concerns, OB/GYNs often advise women who have tested positive for the condition to consult with a general practitioner or specialist for monitoring of the condition after pregnancy. Some OB/GYNs advise against use of hormonal contraception in women with a history of antiphospholipid syndrome also, because of the added risk of blood clots.


Bertolaccini, M.L. and M.A. Khamashta, "Laboratory diagnosis and management challenges in the antiphospholipid syndrome." Lupus 2006. Accesed 20 Feb 2008.

Empson, M., M. Lassere, J. Craig, and J. Scott, "Prevention of recurrent miscarriage for women with antiphospholipid antibody or lupus anticoagulant. Cochrane Database of Systemic Reviews 2005. Accessed 20 Feb 2008.

Rai, R.S. "Antiphospholipid syndrome and recurrent miscarriage." Journal of Postgraduate Medicine 2002. Accessed 20 Feb 2008.

University of Illinois – Urbana/Champaign, "Antiphospholipid Syndrom." Patient Resources. Accessed 20 Feb 2008.

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