New register shows causes of death for Danes 1920–1943

It is now easier for genealogists, epidemiologists, and other researchers to access information about deceased Danes. Death certificates from 1 million Danes from the period 1920 to 1943 have become searchable via the dataset The Historical Cause of Death Register (HDAR).

Photographs of the death certificates have been available on Arkivalieronline for some time, but now the National Archives has used artificial intelligence to read and digitize the certificates, structuring the data into tables. The death certificates are thus both searchable, and it is now possible to use information about causes of death among Danes for statistical calculations.

Freely accessible data with interesting potential

The dataset is freely accessible and includes, among others, these variables:

• Name
• Date of birth and date of death
• Occupation
• Cause of death
• Comorbidities/Associated diseases

The death certificates, which previously existed only as handwritten documents in the archives, have been digitized and interpreted using advanced AI technology.

The National Archives trained the AI to read the certificates using transcriptions of over 100,000 certificates that volunteers had transcribed. This extensive volunteer effort made it possible to convert unstructured text into a searchable and analyzable dataset that provides insight into causes of death and health conditions in Denmark during the first half of the 20th century.

The work was carried out by the National Archives’ Data Science department as part of the Multi-generation Register Project, supported by the Novo Nordisk Foundation, which aims to map family relationships in Denmark from 1920 onward.

Read more about the multi-generation register.

HDAR covers the period prior to the existing digital cause of death register, which encompasses the years 1943–1969.

With HDAR, researchers now have access to a continuous data series enabling new research into hereditary diseases, mortality, and other areas where familial, social, geographical, and genetic factors play a central role.

The dataset can help us understand what contributed to improvements in public health in the 1920s and 1930s. This is an interesting period, where major social reforms expanded the healthcare system with, among other things, municipal hospitals and sickness funds, as well as improved sanitation and housing conditions in cities. Now one can study the effects of the reforms down to the individual level.

Genealogy: Search the Collections

For genealogists and others who wish to search for a specific person’s cause of death, this means one can now search directly by name, date of birth, and date of death to find death certificates from the period 1920 to 1943. This means you may be able to determine which diseases your ancestors had, or what family members in your lineage died from.

Search the death certificates via Search in the Collections, by selecting “Dødsattester 4” as the source collection.

Since HDAR is based on publicly available information, it is freely accessible to anyone wishing to delve into Denmark’s medical history or explore their own family history.

Data in CSV Format and Bonus Material

The dataset is available for download in its entirety in CSV format. When you download the dataset, you receive a ZIP file (112 MB), which includes, in addition to the dataset, both metadata, nomenclature for causes of death, as well as instructions in English and descriptions of data and documentation.

Volunteers Continue to Qualify the Data

The dataset will, according to plan, be continuously upgraded by volunteers who enter sources and proofread via the National Archives’ entry portal. In this way, we ensure that any AI reading errors can be corrected. If you would like to participate in this, contact crowd@rigsarkivet.dk.