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Antiphospholipid Syndrome and Pregnancy: Key Factors in Achieving a Viable Pregnancy
Victoria 
Table of contents
At Tambre, the management of Antiphospholipid Syndrome forms part of our comprehensive fertility assessment, particularly in patients with previous pregnancy losses or implantation failure.
What Is Antiphospholipid Syndrome?
Antiphospholipid syndrome (APS) is an autoimmune disorder that affects the blood and its ability to clot. It is characterised by the persistent presence of autoantibodies directed against phospholipid-binding proteins in the blood, causing it to clot too quickly, creating a systemic pro-thrombotic state.
This significantly increases the risk of developing blood clots in any organ of the body, potentially leading to life-threatening conditions such as stroke, heart attack or deep vein thrombosis.
The exact reason why the immune system attacks itself is not fully understood. However, clinical evidence suggests there may be a genetic predisposition that becomes activated by certain triggers, such as infections (including herpes or glandular fever), as well as other risk factors for thrombosis such as prolonged immobility, surgery, oral contraceptives or pregnancy.
APS can affect both men and women, but is of particular importance in women of reproductive age because of its direct impact on pregnancy (recurrent pregnancy loss, pre-eclampsia, fetal growth restriction).
How Does Antiphospholipid Syndrome Affect Fertility?
APS does not usually cause sterility (the inability to conceive), but rather infertility, meaning difficulty in carrying a pregnancy to term. In other words, fertilisation may occur normally, but during pregnancy APS can lead to:
- Miscarriage
- Pre-eclampsia
- Low birth weight
- Preterm birth
- Stillbirth
- Implantation failure
Why does APS have such a strong impact on pregnancy? On the one hand, antiphospholipid antibodies may interfere with trophoblast invasion (the outer layer of the embryo) into the endometrium, preventing proper embryo attachment. This results in implantation failure.
On the other hand, even if implantation occurs, APS may cause microthrombi in the blood vessels that form the placenta. This restricts the supply of oxygen and nutrients to the fetus and may lead to miscarriage or intrauterine growth restriction.
Is It Possible to Achieve a Full-Term Pregnancy with APS?
Although there is currently no definitive cure to eliminate the antibodies, there is effective treatment to prevent clot formation.
Blood-thinning therapy using anticoagulants and antiplatelet medication (such as low-dose aspirin and heparin) prevents excessive clotting.
Regarding APS and pregnancy, early diagnosis is crucial. It allows anticoagulant treatment to begin promptly, improving placental circulation, reducing the risk of thrombosis and significantly increasing the chances of a successful pregnancy outcome.
How Do We Manage Antiphospholipid Syndrome in IVF Treatment at Tambre?
When pregnancy is your goal, APS cannot be managed in isolation or through a standardised protocol. This complex condition requires coordinated care between specialists in immunology, haematology and reproductive medicine, with specific expertise to ensure accurate diagnosis, appropriate timing of testing and tailored treatment.
Strategic Steps in the IVF Process for Patients with APS
- Early and Comprehensive Diagnosis. One of the most important aspects of APS is that, when detected in time, it can be treated successfully, helping patients avoid the trauma of repeated miscarriages by identifying the underlying cause early. Prompt identification allows anticoagulant therapy and personalised monitoring to be implemented from the outset, improving prognosis and increasing the likelihood of achieving a viable pregnancy.
2. Oestrogen control. Ovarian stimulation in IVF significantly increases oestrogen levels, which may raise the risk of thrombosis in patients with APS. At Tambre, we therefore opt for a fully personalised mild stimulation protocol to minimise this risk.
3. Deferred Embryo Transfer. We may recommend embryo vitrification and transfer in a later cycle. This additional time allows hormone levels to return to baseline and ensures that the uterus is in a safer, more natural state. We often use a modified natural cycle strategy for embryo transfer in order to minimise hormonal medication.
At our Tambre clinics in Madrid and Alicante, we carefully assess which patients require specialised testing, coordinate the optimal timing for investigations and design an individualised protocol that takes into account thrombotic risks associated with ovarian stimulation and endometrial preparation.
In cases of recurrent miscarriage or implantation failure, simply trying again is not enough. Repeating treatment without investigation does not improve outcomes. Identifying the underlying cause does. Only then is it possible to transform a history of loss into a healthy, full-term pregnancy.
If you suspect that antiphospholipid syndrome may be affecting your fertility or you need a personalised assessment, contact Tambre. At our clinics in Madrid and Alicante, our multidisciplinary team specialising in reproductive immunology and pregnancy loss will assess your case comprehensively, using specific diagnostic tests and tailored protocols not only to help you achieve pregnancy, but to support you all the way to holding your healthy baby in your arms.
Frequently Asked Questions About Antiphospholipid Syndrome
Is it possible to have a healthy baby with APS?
Yes. With appropriate treatment, the chances of achieving a healthy, full-term pregnancy are very high.
When is APS most dangerous during pregnancy?
There are two critical periods due to different biological risks:
- First trimester: This is the period of highest risk for early miscarriage, as antibodies may interfere with implantation or early placental development.
- Third trimester (and postpartum): There is an increased risk of severe pre-eclampsia, fetal growth restriction due to placental insufficiency and maternal postpartum thrombosis.
What do positive anticardiolipin antibodies during pregnancy mean?
It means that your blood contains antibodies that may increase the risk of clot formation in the placenta. On their own, they do not confirm a diagnosis of APS, but they require immediate assessment by a haematologist or obstetrician due to the associated risks.
It is common to repeat the test after delivery to determine whether the positivity is persistent or was temporary during pregnancy.
Can heparin before and during pregnancy harm the baby?
No, heparin does not harm the baby. It is the treatment of choice during pregnancy because its molecular structure is too large to cross the placenta.
This means it remains exclusively in your bloodstream to prevent clots and does not reach the fetus. In other words, it is considered safe during pregnancy.
Is IVF safe if I have Antiphospholipid Syndrome?
Yes, but it requires specialised monitoring. Ovarian stimulation increases oestrogen levels, which may heighten thrombotic risk in patients with APS.
For this reason, medication must always be carefully personalised and combined with anticoagulant protection under medical supervision.
Is Antiphospholipid Syndrome hereditary?
APS is not directly inherited from parents to children. However, there may be a familial genetic predisposition to autoimmune conditions.
If there is a family history of diseases such as lupus or rheumatoid arthritis, the likelihood of producing these antibodies may be slightly higher, but APS itself is not considered a hereditary disorder.
