Quality report (OSF): Congenital Malformations
Data description
Statistical presentation
The Register of Congenital Malformations, on which the statistics are based, contains information on major congenital malformations detected among children born in Finland as well as on pregnancy terminations carried out on the grounds of fetal malformations. Data are collected from health care units providing care for newborn children and pregnancy terminations. Submitting the data to the Finnish Institute for Health and Welfare (THL) is mandatory and based on the Act on the National Institute for Health and Welfare (668/2008).
Statistics on congenital malformations have been collected from 1963 onwards, with the latest data reported now for 2022. As data on congenital malformations are mainly collected on a child up to the end of the first year of life, statistics on cases diagnosed during a given calendar year may be published approximately two years after the year under review. Statistics are published as a database report every two years (even years) and as a statistical report every two years (odd years).
Relevance
The main purpose of the statistics on congenital malformations is, through the continuous monitoring of the incidence and quality of congenital malformations, detect any potential new environmental factors that may be harmful to the fetus (teratogens) and prevent the occurrence of congenital malformations by influencing these factors. The statistical data are used for the monitoring of congenital malformations nationally and regionally, and, for example, for planning prenatal screenings, diagnostics and treatment of congenital malformations, and for research on congenital malformations.
The statistics are aimed at healthcare professionals working with reproductive health and congenital malformations, administrative authorities, planning officers and researchers, as well as other parties interested in congenital malformations who need data on the number and prevalence of congenital malformations.
Data content of the statistics
The statistics contain data on the number and prevalence of significant congenital malformations (per 10,000 children born) in Finland. The numbers and prevalence of congenital malformations are examined in live-born and stillborn children and in induced abortions performed due to fetal malformations. The proportions of congenital malformations in all stillbirths and infant deaths are also presented. The numbers and prevalences of certain internationally monitored congenital malformations or groups of congenital malformations are presented at the national level.
The statistics contain data on congenital malformations detected in live-born and stillborn children born in Finland. The statistics also include information on pregnancy terminations carried out on the basis of a confirmed or suspected fetal malformation.
The statistics only present data on the detected major congenital malformations. According to the definition of the Register of Congenital Malformations, these include structural abnormalities, chromosomal abnormalities and certain other congenital abnormalities, such as congenital hypothyroidism. Conditions not reported as congenital malformations include functional disorders of organs and tissues, intellectual disability, congenital infections, minor isolated structural anomalies affecting appearance, normal variations, common minor abnormalities included in the register’s exclusion list, and hereditary or other diseases that are not associated with congenital malformations. This is mainly in line with the guidelines of the European network of population-based registries for the epidemiological surveillance of congenital anomalies, EUROCAT (Guide 1.5). As the Register of Induced Abortions also compiles statistics on abortions performed based on the latter diagnosis types, the figures on terminations due to fetal abnormalities of the Register of Congenital Malformations and the Register of Induced Abortions may differ.
Statistical processing
Source data
The statistics are based on THL’s Register of Congenital Malformations, which receives data on congenital malformations from healthcare providers and genetics laboratories. The Register of Congenital Malformations also collects data on congenital malformations from THL’s Medical Birth Register, the Care Register for Health Care, the Register of Induced Abortions, the Finnish Supervisory Agency, and Statistics Finland's causes of death dataset.
If necessary, the malformation diagnoses are verified with the healthcare units that treated or examined the child/fetus/pregnant person. Data on congenital malformations are primarily collected for the child's first year of life, but the register also receives data on congenital malformations diagnosed later for statistical and research purposes
Data collection
THL receives data on cases of congenital malformations in paper form or electronically, as a notification form or another document, such as a copy of patient records. The data received on forms and other notifications are stored in the database of the Register of Congenital Malformations. A notification of congenital malformations is always submitted as soon as possible after the detection of the abnormality.
Data collection is continuous. Data check-ups are performed regularly, and missing cases and case-specific data are added from other registers. Any unclear cases and diagnoses are checked by contacting hospitals that treated the child/fetus/pregnant person or genetic laboratories.
Data validation
THL strives to check and correct the data as extensively as possible. The aim is to identify missing, incomplete and incorrect data.
The data are verified and complemented using other available register sources, such as THL’s Medical Birth Register, Care Register for Specialised Medical Care, the Register of Induced Abortions, the Finnish Supervisory Agency, and Statistics Finland's causes of death dataset. If necessary, the malformation data are verified and specified by asking for more information from the healthcare units that treated or examined the child/fetus/pregnant person. Over time, the register may receive multiple notifications on the same infant or fetus, all of which will be considered and used continuously to supplement and refine the register data.
The prevalence rates of congenital malformations are compared annually with the international figures published by the European network of population-based registries for the epidemiological surveillance of congenital anomalies (EUROCAT) and the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR).
Data compilation
For classifying and coding of the congenital malformations, the register uses the WHO's ICD-10 and, retrospectively from 1986 onwards, the extension of the ICD-9. Diagnoses are also recorded in written form (in English). The Register of Congenital Malformations follows the practice of EUROCAT (Guide 1.5) by eliminating minor structural abnormalities and some other abnormalities, as well as diseases, from the statistical examinations. The classification and exclusion are partly carried out automatically based on ICD codes, but in a large number of cases, the coding is performed by a specialist in the register based on familiarisation with the data received and obtained from other registers.
Data revision
As the diagnosis of congenital malformations and the detection of their underlying cause, such as a chromosomal abnormality, may occur in later childhood, data are corrected retroactively, and the published annual statistics are subject to minor changes.
Quality assessment of the statistics
Accuracy and reliability
The accuracy of the register data depends on the information recorded at the unit that submitted the notification. To ensure data quality, the data obtained from different sources are compared and, if necessary, the parties responsible for the treatment or examination of the child are asked to provide more information to revise and verify the data. The revised data are entered into the database.
The data content and the data collection practice of the Register of Congenital Malformations were revised in 1985, 1993, 2005 and 2017. Since 2005, data on congenital malformations have also been derived from the Care Register for Health Care, which has further improved the total coverage of the Register of Congenital Malformations.
The prevalence rates for cases with congenital anomalies registered in Finland correspond to the prevalence rates described in the literature and reported in international registers of congenital malformations. The prevalence rates for different types of congenital malformations have been consistent with the findings of other national and international studies on congenital abnormalities.
Timeliness and punctuality
THL produces a statistical report on congenital malformation data in even-numbered years and a database report in odd-numbered years. As congenital malformation data are generally collected by the end of a child’s first year of life, statistics on cases diagnosed during a given calendar year may be published approximately two years after the year under review. As the data are constantly revised, and notifications are also received for children older than 1 year of age, for example, when the diagnosis is further specified, data are corrected retroactively, and there may be minor changes to previously published annual statistics.
Coherence and comparability
Over the decades, there have been changes in the data collection and registration practice of the register, and in hospitals’ reporting activity, which are reflected in the coverage of the register. The development of prenatal screening and fetal diagnostics has led to an increase in the selective terminations of pregnancy on grounds of fetal abnormalities, which is particularly apparent when comparing statistics from the first decades to those published since the 1990s. The reform of the Act on Induced Abortion in 1985 and the redefinition of stillbirth from 1 January 1987 onwards affect the comparability of data entered in the register in different years and decades. The use of the Care Register for Health Care as a data source for the Register of Congenital Malformations since 2005 has improved the total coverage of the Register.
In 2013, the Register of Congenital Malformations started to use the numbers of births from THL's Medical Birth Register, as the basis for prevalence calculations instead of the numbers of births from Statistics Finland. The Medical Birth Register and the Register of Congenital Malformations both collect data on all births taken place in Finland, whereas Statistics Finland collects data on births of Finnish citizens that have taken place in Finland and abroad, but not on births of foreign nationals in Finland. In addition, the Register of Congenital Malformations and the Medical Birth Register record deaths according to year of birth, whereas Statistics Finland records deaths according to year of death.
The statistics use established international concepts and classifications. They are mostly consistent with other national registers and databases that contain data on congenital malformations. For classifying and coding of the congenital anomalies in the register, the ICD-7, -8, -9 and -10 versions of the WHO and, retrospectively from 1986 onwards, the extension of the ICD-9 are used. Diagnoses are also recorded in written form (in English). The basic definitions for reproduction used have principally remained the same (Suomalainen tautien kirjaamisen ohjekirja, THL 2012). The ATC classification and codes are used for medications (Anatomic Therapeutic Chemical classification index).
The Register of Congenital Malformations regularly updates the list of minor congenital malformations to be excluded from the statistics in accordance with the EUROCAT guidelines. In 2022, EUROCAT implemented a broad reform that significantly expanded the list of excluded congenital anomalies compared with previous years. EUROCAT also revised its classification of congenital anomalies based on clinical features and aetiology in 2023. These changes are applied retroactively in the statistics. These changes, in accordance with EUROCAT Guide 1.5, were also introduced to the Register of Congenital Malformations in 2023.
In the 2021 statistics, regional comparisons were shifted, as a result of the wellbeing services counties reform, to use social and health care collaboration areas instead of the former university hospital districts. In regional analyses, the municipality of residence of the child or the woman is used, and the municipal classification of the year of publication or the preceding year is applied.
Institutional mandate
The production of the statistics is based on the Act on the Finnish Institute for Health and Welfare (688/2008) and the Statistics Act (280/2004). One of the official tasks of the Finnish Institute for Health and Welfare is to produce statistical data on the health and welfare of the population, the factors affecting them, and the use and functioning of healthcare and social welfare services to support decision-making, development and research. THL’s statistical production practices are guided by the instructions, recommendations and regulations of Eurostat and the Official Statistics of Finland as well as the principles of statistical ethics.
Data sharing and publishing
THL publishes the data at the time indicated in advance in the statistic publication calendar. The data is made public to all users at the same time.
The statistical reports are public. However, the register data is confidential. The Finnish Social and Health Data Permit Authority Findata grants permits for using the data based on the Act on the Secondary Use of Health and Social Data (552/2019).
Confidentiality
As an authority, the Finnish Institute for Health and Welfare has the obligation to produce compiled data on the health and well-being concerned with the entire country. The data used to draw up THL’s statistics is primarily confidential, and personal data may not be published. The protection of processed data is based on the Act on the National Institute for Health and Welfare (688/2008), the Statistics Act (280/2004), the Act on the Openness of Government Activities (621/1999), the EU General Data Protection Regulation (EU) 2016/679 and the Data Protection Act (1050/2018) as well as other regulations guiding the activities of the Institute.
THL’s datasets are secured at all stages of processing. Data and information systems can only be accessed by persons who have a permit to access certain data for clearly defined purposes. Others do not have the ability to view, process, change or delete data. Written instructions have been drawn up to ensure the data protection of completed statistics. All THL personnel are bound by a confidentiality obligation.