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Pregnancy Health A-Z: Thrombophilia

Thrombophilia is a condition where your blood has an increased tendency to form clots, which can affect you and your baby if you’re pregnant

What causes thrombophilia?

If you suffer an injury, your body will set off a process, which allows the blood to clot and prevent you losing too much blood. This is known as haemostasis and involves different chemicals causing the blood to solidify into a clot, which sticks to the injured part of the blood vessel. There are also natural chemicals in the blood, which act against the clotting system, to stop the blood clotting too much.

But if you have thrombophilia, the clotting system doesn’t work, meaning the blood can clot too much, and this sometimes causes problems during pregnancy.

Who gets thrombophilia?

Some cases of thrombophilia are inherited – a tendency to form blood clots runs in the family and is passed on from your parents to you. ‘In other cases, you can acquire thrombophilia if you have a problem with your immune system, or as a result of another medical problem that has developed,’ says Dr Daghni Rajasingam, a consultant obstetrician and spokesperson for the Royal College of Obstetricians & Gynaecologists.

How is thrombophilia diagnosed?

There are no obvious symptoms of thrombophilia. ‘The first sign that there’s a problem would be a blood clot,’ says Dr Rajasingam. ‘Symptoms of a blood clot vary depending on where it appears. If it’s a clot in the lungs, it could cause breathing problems, but if it the clot occurs in the legs, you may get a swelling there.’

You can check for thrombophilia through blood tests. ‘You will only get tested for thrombophilia during pregnancy if you carry certain risk factors,’ says Dr Rajasingam. ‘These include suffering from recurrent miscarriages, a family history of thrombophilia or if you’ve had a smaller than average baby or a pre-term or still birth after a previous pregnancy.’

If you know you have the condition, or have a family member who has it, make sure you tell your GP or midwife as soon as you start trying for a baby or at your first appointment.

What problems can thrombophilia cause in pregnancy?

It’s important for thrombophilia to be picked up and treated if necessary in pregnancy because it can pose a risk not just to you, but also your growing baby.

‘Thrombophilia could restrict the growth of your baby in the womb or affect how well your placenta works to supply your baby with food and oxygen,’ says Dr Rajasingam. ‘It can also increase your risk of pre-eclampsia, premature birth, miscarriage and stillbirth.’

What is the treatment for thrombophilia?

If you have thrombophilia, treatment will depend on the type of thrombophilia you have, whether you’ve had a blood clot in the past and your family history. ‘Your GP may start off by prescribing 75mg of aspirin, which is a blood thinner, to help reduce the risk of clotting,’ says Dr Rajasingam.

‘Another treatment is low-molecular weight heparin, a drug which acts as an anti-coagulant to prevent blood clotting.’

A recent study carried out at Ottawa Hospital Research Institute, Canada suggested that heparin wasn’t an effective treatment for preventing blood clots and caused unnecessary pain in pregnancy.

‘The RCOG has looked at the study, but at this stage, the national guidance on treatment of pregnant women with thrombophilia has not changed,’ says Dr Rajasingam. ‘There needs to be more studies before we can consider looking into changing the treatment methods.’

What happens when you get deep vein thrombosis?

Deep vein thrombosis (DVT) is when a clot forms in the veins of your legs or pelvis. It’s more common in people who have thrombophilia, but you can also get DVT without having the condition, and it’s more likely to occur when you’re pregnant. ‘That’s because your blood is more prone to clotting to prevent excess blood loss when you give birth,’ says Dr Rajasingam.

Symptoms of DVT can include one or more of the following symptoms in your leg; swelling, pain, warm skin, tenderness and redness, particularly at the back of the leg below the knee.

Can you prevent blood clots or deep vein thrombosis?

Being overweight or dehydrated can increase the risk of blood clots forming, as can being immobile for long periods of time. Wear compression stockings if you’re taking a long haul flight.

If you’re worried or unsure about any symptoms you’re experiencing such as chest pain, shortness or breath or a sore, achey, swollen leg, talk to your GP or midwife straight away.

For more health information, visit the Mother&Baby Clinic section.

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