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Deep vein thrombosis and pulmonary embolism in pregnancy - Blood clots in pregnancy

When you are pregnant, you are at increased risk of blood clots forming in your veins. These can lead to serious medical conditions that need urgent medical help such as:

  • deep vein thrombosis (DVT)
  • pulmonary embolism

Deep vein thrombosis (DVT)

Deep vein thrombosis (DVT) is a serious condition where a blood clot forms in a deep vein in your thigh, calf or pelvis.

Urgent advice: Phone your midwife, GP or maternity unit urgently if you have:

  • pain, swelling or tenderness in 1 leg - usually in your calf area
  • warm or red skin over the affected area
  • a heavy ache in the affected area
  • pain in your calf that gets worse when you bend your foot upwards towards your knee

Not everyone gets symptoms. If you do get symptoms, you may not get all of the symptoms in the list.

DVT is not common in pregnancy. But it is a serious medical condition.

Many pregnant women get swollen ankles and legs at some stage. Swelling on its own doesn’t mean you have a DVT. But if you’re worried, phone your GP, obstetrician or midwife.

Pulmonary embolism

If part of a blood clot breaks off, it can travel in your blood stream and block one of the blood vessels in your lung. This is called a pulmonary embolism (PE).

Emergency action required: Phone 999 or 112 immediately if you:

  • have chest pain or pain in your upper back
  • have sudden difficulty breathing
  • are coughing up blood

PE is not very common. But it can be fatal. Your risk of having a PE increases if you have DVT and it is not diagnosed or treated.

Sometimes PE can happen without obvious signs of a DVT. If you have no symptoms of a DVT, but you are short of breath and have chest pain, it could still be a PE. 

Your risk of DVT or PE in pregnancy

Having a deep vein thrombosis (DVT) increases your risk of a pulmonary embolism (PE).

Pregnancy and giving birth increase your risk of having a DVT because of:

  • changes to your hormones
  • changes to your circulation
  • the veins in the lower part of your tummy and pelvis becoming squashed by your growing womb and baby

This risk continues for the first 6 weeks after you give birth.

When you may be at greater risk of DVT

Your risk of developing DVT during pregnancy is even greater if you:

  • or a close family member have had a blood clot before (mother, father or sibling)
  • suffer from a serious illness or injury
  • are over 35
  • are overweight - especially if your BMI is over 30
  • smoke
  • inject drugs that have not been prescribed
  • travel for longer than 4 hours when you can't move around (such as a long-haul flight)
  • have a multiple pregnancy (expecting twins or more)
  • have had fertility treatment
  • have a medical condition that makes blood clots more likely (called a thrombophilia)
  • have severe varicose veins
  • have poor mobility, for example you are a wheelchair user
  • become dehydrated
  • are admitted to hospital
  • have pre-eclampsia
  • have a caesarean birth
  • lose a lot of blood after the birth

If any of these apply to you, try and speak to your GP before becoming pregnant. If you are pregnant, talk to your GP as soon as possible. You may be advised to go on treatment to prevent a blood clot.

Other medical conditions could also increase your risk. Examples are lung diseases, Lupus and other autoimmune diseases. Talk to your GP or obstetrician if you are worried.

How to reduce the risk of DVT and pulmonary embolism

You can reduce your risk by:

Ask your obstetrician, hospital doctor or midwife whether you should wear compression stockings. These can be prescribed.

Page last reviewed: 30 April 2021
Next review due: 30 April 2024

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.