NewTwin – Genetic, Social and Environmental Factors Impact on Health and Behavior - A Study from the Swedish Twin Registry
This ongoing twin study, initiated in 2021, focuses on all twins born in Sweden. Parents are invited to complete an online questionnaire when their twins are approximately nine months old. The questionnaire includes areas such as pregnancy, neonatal care, screen time and parental health habits. Additionally, saliva samples are collected to determine the twins' zygosity and genotyping. The genotype data is used in genetic association studies to explore diseases, health-related traits and behaviors.
Question Areas:
Parents' education, income and occupation
Fertility treatment
Parents’ health
Parents’ smoking and alcohol habits (current and during pregnancy)
Pregnancy from the mother's perspective
Pregnancy from the twins' perspective
Birth weight and length
Neonatal care
Breastfeeding
Vaccinations
Twin development
Sleep habits of the twins
Zygosity, twin similarities and differences
Family screen time and screen use
Go to data source
https://ki.se/en/research/research-infrastructure-and-environments/core-facilities-for-research/swedish-twin-registry-core-facility
Documentation files
Documentation files
Citation and access
Citation and access
Data access level:
Creator/Principal investigator(s):
Research principal:
Data contains personal data:
Yes
Type of personal data:
Pseudonymised, health data, social security number, pregnancy, lifestyle, exposures, names, addresses
Code key exists:
Yes
Sensitive personal data:
Yes
Citation:
Method and outcome
Method and outcome
Unit of analysis:
Population:
Twins born in Sweden since January 1, 2021, onwards, at approximately 9 months of age.
Study design:
- Cohort study
- Observational study
Description of study design:
Data collection is conducted via a web-based survey. Participation in the study is based on informed consent.
Sampling procedure:
Description of sampling:
Parents of twins born in Sweden, where both twins are alive, are invited to participate when the twins are
between 7 and 10 months old. Twins are excluded if they have protected identity, have emigrated, or if their
parents have opted out of contact with the Swedish Twin Registry. Only complete twin pairs are invited.
Time period(s) investigated:
Variables:
276
Number of individuals/objects:
5800
Response rate/participation rate:
53%
Description of the response rate/participation rate:
The total number of participating twins (through the participation of a parent) is 5 800 out of 10 900 invited (December 2025), resulting in a response rate of 53%. Of the respondents, there is genotype data for about 800 twins.
Samples/material - Collected from scientific collection/biobank
Samples/material - Collected from scientific collection/biobank
Name:
KI Biobank
Type(s) of sample:
DNA from saliva
Data collection - Self-administered questionnaire
Data collection - Self-administered questionnaire
Mode of collection:
Self-administered questionnaire
Description of the mode of collection:
An invitation to a web survey is sent to all parents of Swedish-born twins aged 7–10 months, followed by two reminders. The parents are also asked whether they wish to provide saliva samples from the twins. If they agree, they receive a saliva kit by mail, which they then send to KI Biobank along with a consent form.
Time period(s) for data collection:
2021-11-01 - Ongoing
Data collector:
- Karolinska Institutet
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ROR
Source of the data:
- Registers/Records/Accounts: Medical/Clinical
- Registers/Records/Accounts
Geographic coverage
Geographic coverage
Geographic location:
Geographic description:
Nationwide
Lowest geographic unit:
Parish
Highest geographic unit:
Country
Administrative information
Administrative information
Responsible department/unit:
Department of Medical Epidemiology and Biostatistics [C8]
Ethical Review
Ethical Review
Reviewer:
- Swedish Ethical Review Authority
components.catalogue.resource.content.administrativeInformation.ethicalReview.rorId.srText
ROR
Registration number:
2021-02032
Ethical review information:
Ethical approval: 12 July 2021
Funding
Funding
Funding agency:
- Karolinska Institutet
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ROR
Funding information:
Government grants
Funding agency:
- The Swedish Research Council
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ROR
Award number:
2021-00180_VR
Funding information:
Grant numbers: 2021-00180
Funding agency:
- The Swedish Research Council
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ROR
Award number:
2017-00641_VR
Funding information:
Grant numbers: 2017-00641
