Antiphospholipid syndrome (APS) is an autoimmune condition in which the body makes antibodies that make the blood more likely to clot. In pregnancy, these tiny clots can affect the placenta and lead to repeated miscarriage, late pregnancy loss, pre-eclampsia or a baby that does not grow well. The good news is that APS can be tested for with simple blood tests, and with low-dose aspirin and heparin injections under specialist care, most women with APS go on to have a baby. At Yaal Fertility Centre in Chennai, Dr. Rukkayal Fathima and our team look for APS in every woman who has had repeated pregnancy loss.
What Is Antiphospholipid Syndrome?
Your immune system normally makes antibodies to fight germs. In APS, it also makes antibodies against proteins that sit on the surface of your own cells and in your blood. These are called antiphospholipid antibodies. You may also see the condition called Hughes syndrome or, on lab reports, APLA (antiphospholipid antibodies).
These antibodies tip the balance of the blood towards clotting. Clots can form in the veins, the arteries, or in the very small blood vessels of the placenta. That is why APS can show up in two quite different ways: as a blood clot (for example in the leg) or as problems in pregnancy, and some women have both.
How Antiphospholipid Antibodies Cause Problems
The antibodies do several things at once:
- They make platelets (the blood cells that start a clot) stickier.
- They irritate the lining of blood vessels, which encourages clots to form.
- In early pregnancy, they act directly on the cells of the developing placenta (the trophoblast), making it harder for the placenta to burrow into the womb lining and build a good blood supply.
- They trigger inflammation at the site where the placenta attaches.
Because the placenta is the baby's only source of oxygen and food, even small changes in its blood flow can matter.
Primary and Secondary APS
- Primary APS happens on its own, in a woman with no other autoimmune disease. This is the most common form seen in women with miscarriage.
- Secondary APS happens alongside another autoimmune condition, most often lupus (SLE). These women need care for both conditions, usually shared between an obstetrician and a rheumatologist.
Obstetric APS
When APS shows up mainly as pregnancy problems, with no history of clots elsewhere, doctors call it obstetric APS. This is the form most women reading this article will have, and it is the form that low-dose aspirin and heparin are used for in pregnancy.
How Does Antiphospholipid Syndrome Affect Pregnancy?
APS is one of the few treatable causes of repeated miscarriage, which is why it is always on the list of tests. Our main guide to recurrent pregnancy loss covers the other causes, such as chromosomes, the shape of the womb and hormones.
Recurrent Early Miscarriage
The most common pattern is repeated miscarriage in the first trimester, often before 10 weeks. The antibodies stop the early placenta from attaching well, so the pregnancy cannot continue. Many women have had a normal heartbeat on a scan before the loss.
Late Pregnancy Loss and Stillbirth
APS is also linked with loss after 10 weeks, when a baby with no structural problem dies in the womb. This is less common than early miscarriage but very distressing, and it is a strong reason to test for APS.
Pre-eclampsia
Pre-eclampsia is high blood pressure in pregnancy with signs of strain on the kidneys, liver or other organs. A poorly working placenta releases substances that cause it. Women with APS have a higher chance of pre-eclampsia, and especially of the severe, early form that can mean the baby has to be delivered early.
Poor Baby Growth and Early Birth
When the placenta does not get enough blood, the baby may not grow as expected. Doctors call this fetal growth restriction. Together with pre-eclampsia, this is the main reason some APS pregnancies end in a planned early delivery.
Blood Clots in the Mother
Pregnancy itself makes the blood clot more easily, and APS adds to that. A clot in a leg vein (deep vein thrombosis, or DVT) causes swelling, pain and warmth in one leg. A clot that travels to the lungs (pulmonary embolism) causes sudden breathlessness or chest pain and is an emergency.
APS at a Glance
| Pregnancy problem | Why APS can cause it | What helps |
|---|---|---|
| Repeated early miscarriage | Antibodies stop the early placenta attaching well | Aspirin and heparin from early pregnancy |
| Loss after 10 weeks | Small clots and poor blood flow in the placenta | Treatment plus close scan monitoring |
| Pre-eclampsia | A struggling placenta raises the mother's blood pressure | Aspirin, blood pressure checks, timely delivery |
| Poor baby growth | Less oxygen and food reaching the baby | Growth and Doppler scans, planned delivery |
| Blood clot in mother | APS plus the clotting changes of pregnancy | Heparin during and after pregnancy |
Does APS Affect Getting Pregnant or IVF?
APS does not usually stop you from getting pregnant. Most women with APS conceive without difficulty; the problem is keeping the pregnancy. Some doctors check for APS after repeated failed embryo transfers, but the link with implantation failure is much less clear than the link with miscarriage, and testing every IVF patient is not advised. If embryos have failed to implant more than once, our guide to recurrent implantation failure explains the wider set of checks, and why an IVF cycle may fail covers the common reasons.
If you do need fertility treatment and you have APS, your doctor will plan it with clotting in mind. Hormone medicines used in IVF raise estrogen, which can add to clot risk, so the team decides whether and when heparin should start.
Who Should Have an APS Test?
Testing is advised for women who have had:
- Two or three or more miscarriages in a row, particularly before 10 weeks.
- One or more pregnancy losses after 10 weeks where the baby had no obvious problem.
- An early delivery because of severe pre-eclampsia or a placenta that was not working well.
- A blood clot in a vein or artery without a clear reason, especially at a young age.
- A stroke or mini-stroke at a young age.
- Lupus or another autoimmune disease and plans for pregnancy.
APS testing is not usually advised after a single early miscarriage, because one miscarriage is very common and most often caused by a chance problem with the baby's chromosomes.
How Is Antiphospholipid Syndrome Diagnosed? The APLA Test
The APLA test is not one test but a small panel of blood tests. Diagnosis needs two things together: a typical history (a clot or a pregnancy problem like those above) and blood tests that stay positive over time.
The Three Antibody Tests
| Test | What it looks for | Plain-words meaning |
|---|---|---|
| Lupus anticoagulant (LA) | Whether your blood takes longer than expected to clot in the lab | Despite the name, it is linked with clotting in the body, not bleeding, and it does not mean you have lupus |
| Anticardiolipin antibodies (aCL) | Antibodies against cardiolipin, a fat found in cell walls | Measured as IgG and IgM types; moderate or high levels count |
| Anti-beta2 glycoprotein I antibodies | Antibodies against a blood protein that the APS antibodies bind to | Also measured as IgG and IgM; often the most specific of the three |
Lupus anticoagulant is affected by blood thinners, so the timing of this test matters if you are already on treatment. Tell the lab and your doctor about every medicine you take.
Why the Test Is Repeated 12 Weeks Later
Antiphospholipid antibodies can rise for a short time after an infection, some medicines, or even a recent pregnancy. A single positive result is therefore not enough. If a test is positive, it is repeated at least 12 weeks later. APS is diagnosed only when the antibodies are still present on the second test.
This waiting period can feel long when you want to try again. Your doctor can still talk through a plan with you in the meantime, and it is a good time to complete the other checks for repeated miscarriage.
Understanding Your Report
- All three negative: APS is unlikely. Your doctor looks at other causes.
- One test weakly positive once: often a temporary rise. The repeat test decides.
- Positive on two occasions 12 weeks apart, with a typical history: APS is diagnosed.
- More than one test positive ("double" or "triple" positive): this carries a higher risk, and your care team will plan more closely.
Every lab uses slightly different units and ranges, so always read the result with your doctor rather than comparing numbers between labs.
Other Tests Done Alongside
APS is only one piece of the picture. A full workup for repeated miscarriage usually includes:
- Thyroid tests: TSH and thyroid antibodies. Thyroid problems are common and easy to treat. See thyroid and fertility.
- Blood sugar (HbA1c) and prolactin.
- A 3D ultrasound or hysteroscopy to check the shape of the womb.
- Chromosome tests for both partners, and, when possible, testing of pregnancy tissue.
- Inherited clotting tests (thrombophilia) in selected women, usually those with a personal or strong family history of clots.
Thyroid antibodies and antiphospholipid antibodies are both "autoimmune" findings, but they work very differently and are treated differently. Thyroid problems are managed with thyroid hormone where needed; APS is managed with medicines that reduce clotting.
Treatment for APS in Pregnancy
The aim of treatment is to keep blood flowing smoothly to the placenta. It is always planned by a specialist for your situation, and the exact medicines and doses are decided by your doctor, not by guidelines alone.
Low-Dose Aspirin
Low-dose aspirin makes platelets less sticky. It is usually started before or as soon as you conceive, and continued through most of the pregnancy. It is a very different dose from the aspirin used for headaches. Do not start it on your own; your doctor will tell you whether you need it, which dose, and when to stop.
Heparin Injections
Heparin is a blood thinner given as a small injection under the skin of the tummy or thigh, usually once a day. The type used in pregnancy is called low molecular weight heparin (LMWH). It is usually started once a pregnancy is confirmed on a scan or blood test.
- Heparin does not cross the placenta, so the baby is not exposed to it.
- Most women learn to give the injection themselves, or a family member learns. It takes only a minute once you are used to it.
- Small bruises at the injection site are common and harmless.
- The dose depends on your weight, your history and your test results, and it may change during pregnancy.
Aspirin and Heparin Together
For women with obstetric APS and repeated miscarriage, aspirin plus heparin is the standard approach. For women with APS who have had a blood clot in the past, the treatment is planned more like full anticoagulation, often with a higher heparin dose, and a haematologist may be involved.
Women Already on Warfarin
Some women with APS take warfarin long-term after a clot. Warfarin can harm a developing baby in early pregnancy, so it must be switched to heparin either before conception or as soon as pregnancy is confirmed. If you take warfarin and are planning a pregnancy, see your doctor before you start trying.
What Is Not Routinely Advised
Steroids, intravenous immunoglobulin (IVIG) and other immune treatments have been tried for APS, but they have not been shown to work better than aspirin and heparin and they carry their own risks. They are not part of routine care. In a small number of women whose pregnancies have had problems despite standard treatment, a specialist may consider additional medicines; this is a case-by-case decision.
Planning a Pregnancy With APS
The best outcomes come from planning before you conceive, not after a positive test.
A Preconception Visit
A preconception care visit lets your doctor:
- Confirm the diagnosis and review all your test results.
- Check your blood pressure, kidney function, blood count and thyroid.
- Review every medicine you take and switch any that are unsafe in pregnancy.
- Start folic acid, which every woman planning pregnancy needs.
- Write down a clear plan: when to start aspirin, when to start heparin, and who to call when you get a positive test.
When You Get a Positive Test
Contact your care team as soon as your home test is positive. An early blood test and scan confirm the pregnancy, and heparin is usually started at this point if it is part of your plan. Do not wait for your next routine appointment.
Looking After Yourself
- Stay active and keep moving, especially on long journeys.
- Drink enough water, particularly in the Chennai heat.
- Do not smoke, and avoid second-hand smoke.
- Keep a healthy weight before pregnancy.
- Know the warning signs of a clot (a painful, swollen leg; sudden breathlessness; chest pain) and seek care immediately if they appear.
Monitoring During an APS Pregnancy
An APS pregnancy is looked after as a high-risk pregnancy. This does not mean something will go wrong. It means you are watched more closely so that any problem is picked up early.
Scans and Checks Through Pregnancy
| Stage | What is usually checked |
|---|---|
| First trimester | Early scans to confirm the heartbeat; baseline blood tests and blood pressure |
| Second trimester | The detailed anatomy scan; often a Doppler scan of the blood flow in the womb arteries |
| Third trimester | Regular growth scans; blood pressure and urine checks for pre-eclampsia; Doppler of the baby's blood flow |
| Near term | Closer checks on the baby's wellbeing and a plan for the timing of birth |
Your doctor will set the exact schedule. Regular antenatal care visits and ultrasound scans are the backbone of this monitoring.
Warning Signs to Report Straight Away
- Bleeding from the vagina.
- Severe headache, blurred vision, or pain under the ribs on the right (possible pre-eclampsia).
- Sudden swelling of the face, hands or feet.
- The baby moving less than usual in later pregnancy.
- A painful, swollen leg, sudden breathlessness or chest pain.
Planning the Birth
Most women with APS can aim for a normal delivery; APS on its own is not a reason for a caesarean. Because heparin affects bleeding, your doctor will plan when to pause it before labour, an induction or a caesarean, so that an epidural or spinal anaesthetic can be given safely. Tell the labour ward team that you are on heparin as soon as you arrive.
After the Baby Is Born
The weeks after birth carry the highest risk of blood clots for any woman, and more so with APS. Heparin is usually continued for some weeks after delivery, for a length of time your doctor decides. Heparin and low-dose aspirin are generally considered compatible with breastfeeding.
Women with APS who have had only pregnancy problems are usually not kept on blood thinners for life, but your doctor may advise long-term low-dose aspirin. Because APS raises clot risk, estrogen-containing contraceptive pills are usually avoided; progestogen-only methods or a coil are safer choices. Discuss this before you leave hospital.
What Is the Outlook With Treatment?
Without treatment, women with APS have a high chance of losing a pregnancy. With early diagnosis, low-dose aspirin, heparin and careful monitoring, the picture changes greatly, and most women with APS go on to have a live baby. Some pregnancies still face problems such as pre-eclampsia or early birth, which is why monitoring continues to the end.
Many women in Chennai come to us after two, three or more losses, having been told "it is just bad luck". Finding a treatable cause like APS can be a turning point, both medically and emotionally.
Coping With Repeated Loss
Repeated miscarriage is a real grief, and anxiety in the next pregnancy is normal. Talk openly with your partner and your doctor, and ask for extra early scans if they help you feel reassured. Family members, often the mother or mother-in-law, can be a great support during the injections and appointments when they understand what APS is.
Myths About APS and Miscarriage
| Myth | Fact |
|---|---|
| A miscarriage was caused by something I did | APS is an immune condition; it is not caused by work, travel, food or stress |
| One positive APLA test means I have APS | The test must stay positive 12 weeks later, along with a typical history |
| Heparin will harm my baby | Heparin does not cross the placenta |
| Lupus anticoagulant means I have lupus | It is the name of a lab test; most women with it do not have lupus |
| With APS I can never have a baby | With treatment, most women with APS do have a baby |
| I should take aspirin as soon as I get pregnant, just in case | Only take aspirin if your doctor advises it, at the dose they set |
Frequently Asked Questions About Antiphospholipid Syndrome
Can I have a healthy baby with antiphospholipid syndrome?
Yes. With low-dose aspirin, heparin injections and close monitoring under a specialist, most women with APS go on to have a healthy baby.
What is the APLA test?
It is a set of blood tests for antiphospholipid antibodies: lupus anticoagulant, anticardiolipin antibodies and anti-beta2 glycoprotein I antibodies. A positive result must be repeated at least 12 weeks later to confirm APS.
How does antiphospholipid syndrome cause miscarriage?
The antibodies stop the early placenta from attaching well and cause tiny clots in its blood vessels. This cuts the supply of blood, oxygen and food to the pregnancy.
Are heparin injections safe in pregnancy?
Yes. Low molecular weight heparin does not cross the placenta, so the baby is not exposed to it, and it is widely used in pregnancy under specialist care.
When should I start treatment for APS?
Aspirin is often started before or at conception, and heparin once pregnancy is confirmed. Plan this with your doctor before you start trying.
Can antiphospholipid syndrome be cured?
APS cannot be cured, but it can be managed well. Treatment in pregnancy protects the placenta, and many women need little or no treatment between pregnancies.
Should I be tested after one miscarriage?
Usually not, as a single early miscarriage is common and most often due to a chance chromosome problem. Testing is advised after repeated losses, a loss after 10 weeks, or early severe pre-eclampsia.
Do I need a caesarean if I have APS?
No. APS alone is not a reason for a caesarean, but your doctor will plan when to pause heparin before labour or any procedure.
Antiphospholipid Syndrome Care at Yaal Fertility Centre, Chennai
At Yaal Fertility Centre, our recurrent pregnancy loss team led by Dr. Rukkayal Fathima, MRCOG (UK) checks for APS as part of a complete evaluation after repeated miscarriage. If APS is found, we plan your treatment before you conceive and follow you closely through pregnancy, working with physicians and specialists where needed, so you know exactly what to do at every stage.
You can see our team at any of our eight centres across Chennai: Kilpauk, Mylapore, Thiruvanmiyur, Pallikaranai, Madipakkam, Red Hills, Velappanchavadi and Tambaram.
If you have had repeated miscarriages, or you have been told your APLA test is positive, book a consultation with Yaal Fertility Centre.
Written by
Dr. Rukkayal Fathima
Specialist at Yaal Fertility Centre, Chennai. Providing expert guidance on fertility and women's health.
