University of Southern Denmark
The Danish Medical Birth Register
Bliddal, Mette; Broe, Anne; Pottegård, Anton; Olsen, Jørn; Langhoff-Roos, Jens
Published in:
European Journal of Epidemiology
DOI:
10.1007/s10654-018-0356-1
Publication date:
2018
Document version:
Accepted manuscript
Citation for pulished version (APA):
Bliddal, M., Broe, A., Pottegård, A., Olsen, J., & Langhoff-Roos, J. (2018). The Danish Medical Birth Register.
European Journal of Epidemiology
,
33
(1), 27–36. https://doi.org/10.1007/s10654-018-0356-1
Go to publication entry in University of Southern Denmark's Research Portal
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1
The Danish Medical Birth Register
M Bliddal
1
, A Broe
2&3
, A Pottegård
2
, J Olsen
4
, J Langhoff-Roos
5
1
Odense Patient Data Explorative Network (OPEN), Department of Clinical Research,
University of Southern Denmark and Odense University Hospital, Odense, Denmark,
ORCID: orcid.org/0000-0002-7637-3730
2
Clinical Pharmacology and Pharmacy, Department of Public Health, University of Southern
Denmark, Odense, Denmark, ORCID: orcid.org/0000-0002-4149-8808
3
Department of Clinical Biochemistry and Pharmacology, Odense University Hospital,
Odense, Denmark, orcid.org/0000-0001-9314-5679
4
Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Denmark
5
Department of Obstetrics, Rigshospitalet, University of Copenhagen, Copenhagen,
Denmark, ORCID: orcid.org/0000-0003-2838-2533
Acknowledgement
We would like to acknowledge the Danish Health Data Authority for valuable help during the
writing process of this data resource profile.
Corresponding author:
Mette Bliddal
E-mail: mette.bliddal@rsyd.dk
Phone: +45 2943 7912
2
Abstract
The Danish Medical Birth Register was established in 1973. It is a key component of the
Danish health information system. The register enables monitoring of the health of pregnant
women and their offspring, it provides data for quality assessment of the perinatal care in
Denmark, and it is used extensively for research. The register underwent major changes in
construction and content in 1997, and new variables have been added during the last 20 years.
The aim was to provide an updated description of the register focusing on structure, content,
and coverage since 1997.
The register includes data on all births in Denmark and comprises primarily of data from the
Danish National Patient Registry supplemented with forms on home deliveries and stillbirths.
It contains information on maternal age provided by the Civil Registration System.
Information on pre-pregnancy body mass index and smoking in first trimester is collected in
early pregnancy (first antenatal visit). The individual-level data can be linked to other Danish
health registers such as the National Patient Registry and the Danish National Prescription
Registry. The register informs several other registers/databases such as the Danish Twin
Registry and the Danish Fetal Medicine Database.
Aggregated data can be publicly accessed on the Danish Health Data Authority web page
(www.esundhed.dk/sundhedsregistre/MFR). Researchers can obtain access to individual-level
pseudo-anonymised data via servers at Statistics Denmark and the Danish Health Data
Authority.
Key words: Registers, research design, medical record linkage, nationwide birth register
3
Introduction
The Danish Medical Birth Register (MBR) is a key component of the Danish health
information system. The register enables health of pregnant women and their offspring to be
monitored as well as facilitate quality control of perinatal care. In addition, it provides data
for Statistics Denmark and eSundhed.dk. These institutions provide aggregated annual data
from the MBR available to the public as well as individual-level data for research. Data from
the MBR is used alone or linked with other Danish register data in epidemiological research
[1,2].
The register was established in 1973 based on paper birth forms. The first systematic data
collection started in 1968 and the first statistical analyses published; no electronic data was
collected before 1973. Descriptive papers on the register have been published in 1986 [3] and
in 1998 [4]. Major changes in construction and content of the register were implemented in
1997, with the paper from 1998 describing the old version [4]. In 1997, the electronic
registration of births replaced paper forms and data has since been recorded in a slightly
revised form to the Danish National Patient Registry (NPR) and fed directly into the MBR.
The Danish National Patient Registry is a nationwide register which holds information on all
somatic hospitalizations in Denmark since 1977. All psychiatric, outpatient, and emergency
department contacts were added in 1995 [5]. Due to changes in clinical practice as well as a
wish to add supplementary information, new variables have been added to the register during
the last 20 years. Since then, the register has only been described briefly in papers within
narrow specific research areas [6,7] and in publications including medical birth registers from
all Nordic countries [8,9].
The aim of this paper is to provide an updated description of the register focusing on
structure, content, and coverage since 1997, including a brief description of selected variables
4
and the development over time. Further, we briefly describe the Danish legislation and how to
access data from the MBR.
Historical background
The nationwide MBR was established in 1973, and data on all live and stillbirths by women
with residence in Denmark giving birth in Denmark have been registered in the MBR since.
The Danish Health Data Authority administers the MBR and all other Danish national health
registers. Even before 1973, midwives recorded some structured information on maternal
health, complications and interventions during pregnancy and delivery, and infant outcome in
birth protocols. These protocols are kept in the Danish National Archives and from 1910 the
registration is considered nearly complete (personal communication, the Danish National
Archives: www.sa.dk).
Structure and content
The MBR holds medical and civil registration information. Since 1968, all residents in
Denmark are registered in the Danish Civil Registration System with a unique 10-digit civil
registration number (CPR number), which is used in all official registrations [10]. Thus, all
newborns are assigned a CPR number at delivery in Denmark or upon immigration to
Denmark. At assignment, the unique CPR number of the child is linked to the CPR number of
the parents in the Civil Registration System [10]. Since 2002, stillbirths have also received a
CPR number for administrative purposes. The Danish Civil Registration System holds
information on migration, vital status and selected demographic data on the parents [10]. To
be noted, parents in the MBR are the (assumed) biological parents, whereas the parents
registered in the Danish Civil Registration System are the legal parents and thus not
necessarily equivalent to the former (unless a paternity trial has been resolved).
