A DVT can occur at any time during your pregnancy, and although not common, pregnancy and postpartum are risk factors for thrombosis with events occurring in approximately 1–2 in every 1000 women.

Risk factors that may increase VTE risk in pregnancy and postpartum include:

  • Being over 35 years of age
  • Have already had three or more babies
  • History of previous venous thrombosis
  • Family history of a mother, father, brother or sister who has had a venous thrombosis
  • Existing diagnosis of a thrombophilia
  • Have a medical condition such as heart disease, lung disease or arthritis
  • Overweight with a BMI over 30
  • A smoker or if you use intravenous drugs
  • During pregnancy
  • If you are admitted to hospital
  • Multiple pregnancy
  • Become dehydrated or less mobile in pregnancy due to, for example, vomiting in early pregnancy
  • Are immobile for long periods of time
  • Have pre-eclampsia

RCOG clinical guideline: Reducing the Risk of Thrombosis and Embolism during Pregnancy and the Puerperium.