In cooperation with researchers from the University of Groningen participants' place of birth has been transformed to the variable 'province of birth'. Linkage (see below) resulted in a province of birth for ~162,500 Lifelines participants, which is available in the Lifelines catalogue (sections: demographics (nationality & ethnicity) and secondary & linked variables).

Place of birth was obtained from the Personal Records Database Netherlands (basisregistratie personen - BRP). In the first phase of the linkage place of birth was linked to “Woonplaatsen in Nederland” (i.e. residences in the Netherlands) obtained from Statistics Netherlands (CBS) in 2011.
After this first phase of linkage <200 places of birth couldn't be matched and have, therefore, been matched by hand. Four reasons for a mismatch have been identified

1. Name of municipality instead of place (match generated by researchers University of Groningen)
2. Blanks in name that didn't correspond with the file from Statistics Netherlands (match generated by researchers University of Groningen)
3. Former name is used (match generated by researchers University of Groningen)
4. Former municipality name is used (match generated by Lifelines)

No province of birth has been generated if:

• Participant was born outside of the Netherlands
• Place of birth was matched to two provinces in the file from Statistics Netherlands