Blood Clots & Bleeding Disorders

Blood clots in pregnancy, or clots in the past before you were pregnant, mean that your pregnancy is high risk. Other blood problems that we commonly see in pregnant women are thrombophilias, bleeding tendencies and platelet problems.

What is a blood clot?

A blood clot is basically a solid lump of blood cells. If a blood clot forms inside one of your vessels, it blocks off the flow of blood. Blood clots in pregnancy, or before you fall pregnant, make you high risk.

The effect of the blood clot depends on where it is located. For example, a deep venous thrombosis (DVT) is a clot in the veins of the leg. The symptoms of a DVT are swelling and pain in the leg. A pulmonary embolus (PE) is a clot in the lung, so the symptoms include sudden shortness of breath and pain when you breathe.

What is a thrombophilia?

Thrombophilia roughly translates as “likes to clot.” It means your blood has an increased tendency to form blood clots. If you have a thrombophilia, you are even more likely to develop blood clots in pregnancy.

You can be born with a thrombophilia (including inherited types that run in families). Alternatively, a tendency can develop later in life due to auto-immune disease, other underlying medical problems, lifestyle factors and medications.

What is a “bleeding tendency”?

A bleeding tendency is the opposite of a thrombophilia. It means you are more likely to bleed and the bleeding is harder to stop.

A woman might know that a bleeding tendency runs in her family. Otherwise, she might have a history of heavy periods, easy bruising or haemorrhage after dental work.

The most well-known bleeding tendency is haemophilia, but there are others such as von Willebrand disease.

What are platelets?

Platelets are one of the cell types that make up blood (along with red and white blood cells). When you cut yourself, platelets rush to the damaged section of blood vessel and form a plug to stop the bleeding.

If you don’t have enough platelets, you can bleed dangerously even after a relatively minor injury.

On the other hand, if you have too many platelets you are more likely to develop blood clots.

What effect will my blood disorder have on my pregnancy?

Pregnancy itself makes a woman’s blood more prone to clotting. If a woman with a thrombophilia becomes pregnant, she is at especially high risk of a blood clot. Your obstetrician should discuss the role of blood-thinning medication (aspirin or heparin) with you early in pregnancy.

Women with a thrombophilia are also at higher risk of certain pregnancy complications including miscarriage, bleeding from the placenta, fetal growth restriction and stillbirth. Your baby will need closer monitoring throughout pregnancy.

At the other end of the spectrum are women with a bleeding tendency, who are particularly at risk of haemorrhage following birth. Your obstetrician and haematologist may need to make special plans for your birth to reduce this risk. If the bleeding disorder is inherited, there is a risk that your baby will also be affected. You will need to discuss this with a geneticist and Maternal-Fetal Medicine specialist.

Have you looked after many women with blood clots in pregnancy?

Yes, Dr Walsh has looked after hundreds of women with a history of clots, thrombophilias, bleeding disorders and low platelets. While working in Ireland, he helped to run a weekly joint obstetric / haematology antenatal clinic for women with precisely this type of problem.

As always, this information is intended for general educational purposes only. It is not medical advice. Please discuss any medical issues with your own doctor. Read our full medical disclaimer here.