UK Obstetric Surveillance System (UKOSS)


A new study, Fibrinogen Deficiency in Pregnancy, will be starting on the 1st of November 2017 and will be collecting cases until the 31st of October 2018. This study will appear on the November report which will be requested in early December. Please see the Fibrinogen Deficiency in Pregnancy study page for the case defintion and further information.

The Seasonal Influenza in Pregnancy study has been extended for another year and will now finish collecting cases on the 31st of October 2018. Cases occurring AFTER the 1st of November 2017 will require the completion of two control data collection forms. More details can be found on the Seasonal Influenza in Pregnancy study page.

If you have any questions regarding either of these studies please contact the UKOSS team (

UKOSS: A national system to study rare disorders of pregnancy


To develop a UK-wide Obstetric Surveillance System to describe the epidemiology of a variety of uncommon disorders of pregnancy.


  • To use this system to lessen the burden on reporting clinicians of multiple requests for information from different sources.
  • To enable the conduct of parallel cohort or case-control as well as descriptive epidemiological studies.
  • To use the knowledge gained to make practical improvements in prevention and treatment and allow for more effective service planning.
  • To provide a system capable of responding rapidly to emerging conditions of major public health importance.

Why study rare disorders?

Rare conditions of pregnancy:

  • Are under-researched.
  • Our understanding of them is poor.
  • Any interventions used in current clinical practice are rarely based on robust evidence.
  • Routine sources of information are limited or unreliable.
  • Comprehensive studies require a large collaboration to identify relatively small numbers of women.
  • Requests for information from multiple sources about different uncommon disorders can place an unacceptable burden on reporting clinicians.

This single, routine, reporting system avoids these problems and has the benefit of allowing the range of conditions under surveillance to change over time.

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Introduction to UKOSS presentation