What is antiphospholipid syndrome (APS) and how does it affect pregnancy?

By (gynecologist), (gynecologist) and (embryologist).
Last Update: 05/04/2022

Antiphospholipid syndrome, antiphospholipid antibody syndrome, Hughes syndrome or APS is a systemic autoimmune disease. APS is characterized by arterial, venous or small vessel thrombosis. In addition, this syndrome is also associated with miscarriages, fetal losses and premature births.

APS is associated with the presence of antiphospholipid antibodies (AAF). These molecules alter the function of phospholipids and create a procoagulant (which favors coagulation) and proinflammatory state, which increases the risk of thrombosis.

What is antiphospholipid syndrome?

It is an autoimmune disease characterized by the appearance of arterial or venous blood clots. In addition, APS is associated with recurrent miscarriages, fetal loss and preterm delivery.

APS is a rare disease (40-50 cases / 100,000 inhabitants). Despite this, the incidence of FAS is higher in younger women, often diagnosed between the ages of 30-40 years.

A distinction can be made between primary antiphospholipid syndrome or secondary antiphospholipid syndrome if it is associated with another disease, usually systemic lupus erythematosus (SLE). However, APS may be associated with other autoimmune diseases, infections, neoplasms, some drugs and other diseases.

Antiphospholipid antibodies (AAF)

Antiphospholipid antibodies (AAF) play an important role in the development of this syndrome. AAFs are antibodies that the immune system produces erroneously, as they will affect the function of phospholipids. This will create a state of hypercoagulation which increases the risk of thrombosis.

The main antiphospholipid antibodies are:

  • Lupus anticoagulant (LA).
  • Anticardiolipin antibodies.
  • Anti-β2glycoprotein I antibodies (Anti-β2GPI).

The reason for the occurrence of these AAFs is not known. An external factor in a genetically predisposed person may be the cause of its appearance.


There are occasions when no symptomatology is present despite having AAF. However, the presence of AAF predisposes to an increased risk of thrombosis in certain situations such as:

  • Prolonged rest period.
  • Pregnancy.
  • Surgeries
  • Arterial hypertension and diabetes mellitus.
  • Obesity.
  • Ingestion of oral contraceptives (estrogens).
  • Smoking.
  • Autoimmune disease such as systemic lupus erythematosus (SLE).
  • Neoplasms.

However, FAS can have clinical manifestations as varied as those mentioned below:

  • Venous, arterial or small vessel and recurrent thrombosis.
  • Recurrent miscarriage or fetal loss, preterm birth, preeclampsia, eclampsia and fetal growth retardation.
  • Stroke and transient ischemic attack.
  • Cognitive impairment and other neurological manifestations such as migraine.
  • Thrombocytopenia (low platelet count).
  • Marble-like or marmoreal skin (livedo reticular).

It should be noted that the symptoms and severity of a blood clot will depend on the organ affected and the extent of the involvement.


The diagnosis of FAS is usually made in patients who have had a history of thrombosis, recurrent miscarriages, fetal loss or premature delivery with no other apparent explanation. This constitutes, broadly speaking, the clinical criteria for its diagnosis.

However, laboratory criteria are also necessary for the diagnosis of definitive FAS. This criterion is determined by a blood test to check for any of the 3 AAF mentioned above. However, in case of a positive result for any FFA, the analysis must be repeated in a period of time longer than 12 weeks to confirm the result.


First of all, situations that may increase the risk of thrombosis should be avoided and treated.

Currently, the treatment of APS is aimed at decreasing the risk of blood clot formation. In patients with positive AAF, but without clinical symptoms, spot treatment can be administered in situations that increase their risk of thrombosis. In patients at higher risk, treatment may be indefinite.

In the face of clinical manifestations of FAS, treatment will vary according to the individual case.

Treatment during pregnancy

In the case of a pregnant woman, maternal thrombosis and pregnancy loss must be controlled and avoided. However, the specialist will study the treatment individually.

Acetylsalicylic acid and heparin are drugs frequently used in pregnancy. The follow-up of the entire gestation period requires strict multidisciplinary control by obstetric specialists, hematologists and rheumatologists or internists with experience in this type of pathology.

On the other hand, ovarian stimulation performed in assisted reproduction techniques produces an increase in estrogen levels. Because of this, the risk of thrombosis may be increased with respect to the general population, especially in patients prone to develop thrombosis.

Assisted procreation, as any other medical treatment, requires that you rely on the professionalism of the doctors and staff of the clinic you choose. Obviously, each clinic is different. Get now your Fertility Report, which will select several clinics for you out of the pool of clinics that meet our strict quality criteria. Moreover, it will offer you a comparison between the fees and conditions each clinic offers in order for you to make a well informed choice.

In these cases, appropriate antithrombotic treatment should be administered and it is recommended to avoid ovarian hyperstimulation syndrome.

FAQs from users

Can I get pregnant with APS?

By Blanca Paraíso M.D., Ph.D., M.Sc. (gynecologist).

Antiphospholipid syndrome or APS is an autoimmune disorder characterized by thrombotic events and/or problems in pregnancy associated with the presence of antiphospholipid antibodies in the blood, such as anticardiolipin antibodies, anti-beta2-glycoprotein antibodies or lupus anticoagulant. It can occur in isolation or in the context of other autoimmune diseases such as lupus erythematosus sitematosus.

Complications in pregnancy include miscarriages (especially those after 10 weeks), preeclampsia or placental insufficiency. The mechanism by which PAS produces these adverse events could be a defect in placentation. Thus, in women with APS, the risk of thrombombolism during pregnancy or postpartum is 5-12% (in the general population it would be <0.10%).Treatment of APS during pregnancy reduces the likelihood of thrombosis and pregnancy complications. The medication that is prescribed will depend on the problems that the woman has presented, but normally consists of acetylsalicylic acid or ASA (low-dose aspirin) and heparin, although sometimes other drugs such as hydroxychloroquine may be used. If thrombosis has occurred, lifelong treatment with anticoagulants will probably be necessary, not only during pregnancy. If the PBS has only been expressed as complications of pregnancy it can probably be withdrawn 6 weeks after delivery.

What is antiphospholipid syndrome?

By Gorka Barrenetxea Ziarrusta M.D., Ph.D. (gynecologist).

Antiphospholipid syndrome (APS) is an entity with specific clinical and analytical features independent of other autoimmune entities. The etiopathogenesis of the condition is unknown. This means that the mechanism by which antiphospholipid antibodies cause fetal losses is not known. However, it seems that a coagulation phenomenon (thrombosis) may be at the basis of the problem.

Ultimately, pregnant patients affected by SAP are at risk of recurrent miscarriages and recurrent late fetal losses. Therefore, it is imperative to rule out this syndrome in these patients by determining the possible presence of APL or ACA.

Once other causes of miscarriage have been ruled out, and a diagnosis of SAP has been made, treatment will be based fundamentally on drugs with an antiplatelet (acetylsalicylic acid) and/or anticoagulant (Heparin) effect.

Why is anticoagulation important in antiphospholipid syndrome (APS)?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

Treatment with anticoagulants is of great importance in APS, since these patients have a hypercoagulable situation that increases the risk of thrombosis and obstetric problems.

What does it mean that FAS is an autoimmune disease?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

In an autoimmune disease the body's immune system produces antibodies that will attack the body itself. In the case of FAS, these antibodies alter the function of phospholipids creating a situation of hypercoagulation.

What is catastrophic antiphospholipid syndrome?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

This is the most severe form of APS. This type of APS is characterized by multiple thromboses of sudden onset, leading to multiple organ involvement (either simultaneously or within a short period of time). Multi-organ failure can make catastrophic APS fatal.

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If you would like to learn more about immunological infertility, you can visit the following link: Immunological infertility: types, causes and treatments.

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FAQs from users: 'Can I get pregnant with APS?', 'What is antiphospholipid syndrome?', 'Why is anticoagulation important in antiphospholipid syndrome (APS)?', 'What does it mean that FAS is an autoimmune disease?' and 'What is catastrophic antiphospholipid syndrome?'.

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Authors and contributors

 Blanca Paraíso
Blanca Paraíso
M.D., Ph.D., M.Sc.
Bachelor's Degree in Medicine and Ph.D from the Complutense University of Madrid (UCM). Postgraduate Course in Statistics of Health Sciences. Doctor specialized in Obstetrics & Gynecology, and Assisted Procreation. More information about Blanca Paraíso
License: 454505579
 Gorka Barrenetxea Ziarrusta
Gorka Barrenetxea Ziarrusta
M.D., Ph.D.
Bachelor's Degree in Medicine & Surgery from the University of Navarra, with specialty in Obstetrics and Gynecology from the University of the Basque Country. He has over 30 years of experience in the field and works as a Titular Professor at the University of the Basque Country and the Master's Degree in Human Reproduction of the Complutense University of Madrid. Vice-president of the SEF. More information about Gorka Barrenetxea Ziarrusta
License: 484806591
 Silvia Azaña Gutiérrez
Silvia Azaña Gutiérrez
B.Sc., M.Sc.
Graduate in Health Biology from the University of Alcalá and specialized in Clinical Genetics from the same university. Master in Assisted Reproduction by the University of Valencia in collaboration with IVI clinics. More information about Silvia Azaña Gutiérrez
License: 3435-CV

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