The cumulative incidence of venous thromboembolism during pregnancy and puerperium

Objectives. The aim of the study was to estimate the cumulative incidence of venous thromboembolism during pregnancy and the puerperium. Methods. All diagnoses concerning venous thromboembolism in the Hospital Discharge Registry from a Danish County in women less than 49 years of age from 1984 to 1994 were included. The number of deliveries in the County during this period was obtained from The Medical Registry of Birth. Results. The cumulative incidence of venous thromboembolism during pregnancy and puerperium was 0.85 (95% CI: 0.64-1.11) per 1000 deliveries. The cumulative incidence was 0.49 (95% CI: 0.28-0.80) in 1984-89 but increased to 1.23 (95% CI: 0.87-1.69) after the introduction of ultrasound. Conclusion. The risk of diagnosed venous thromboembolism is low but estimates of the incidence are probably procedure dependent.