Table 2.

Description of the data sources for both study arms

Register/source	Type	Data	Time	Subject	Arm
Medical records	Hospital and primary health care records	Index pregnancy and delivery data OGTT values	Baseline	Mo	Case-control
		Delivery data Primary health care data (growth, development, health)	Baseline Follow-up	C	Case-control
Questionnaire		Background characteristics, lifestyle factors, family history	Baseline	Mo/Fa	Case-control
National Institute for Health and Welfare	Medical Birth Register	Identification of the index women and pregnancy data	Baseline	Mo	Case-control Register-based
		Previous and following pregnancies	Baseline Follow-up	Mo	Case-control Register-based
		Births of the parents	Baseline	Mo/Fa	Register-based
	Register on congenital malformations		Baseline Follow-up	Mo/Fa/C Mo/Fa/C/S	Case-control Register-based
	Care Register for Health Care (HILMO)	Diagnoses Procedures Hospitalization	Baseline Follow-up	Mo/Fa/C Mo/Fa/C/S/G	Case-control Register-based
	Register of Primary Health Care Visits (AvoHILMO)	Reasons for visits/diagnosesProceduresOutpatient visits	Follow-up (from 2011a)	Mo/Fa/C Mo/Fa/C/S/G	Case-control Register-based
	Register of Social Welfare Benefits		Years 2005-09	Mo/Fa	Register-based
	Cancer Register		Baseline Follow-up	Mo/Fa/C Mo/Fa/C/G	Case-control Register-based
	Cancer Screening Registry	Breast cancer screening	Follow-up	Mo	Case-control Register-based
		Cervical cancer screening		Mo	Case-control Register-based
Statistics Finland	Educational degree and occupation		Baseline	Mo/Fa	Register-based
	Income and socioeconomic status		Years 2005–09	Mo/Fa	Register-based
	Date and causes of death		Follow-up	Mo/Fa/C Mo/Fa/C/S/G	Case-control Register-based
Population Register Centre	Identification of the father and grandparents of index children		Baseline	Fa/G	Register-based
	Identification of previous children		Baseline	Fa	Register-based
Social Insurance Institution of Finland		Reimbursement of drugs	Baseline Follow-up	Mo/Fa/C Mo/Fa/C/S/G	Case-control Register-based
		Purchase of medicine	Follow-up	Mo/C	Case-control Register-based
	Prescription centre and archive	Electronic prescriptions	Follow-up (from 2017a)	Mo/C	Case-control Register-based
Matriculation Examination Board	Matriculation examination scores			Mo/Fa	Register-based
DNA sample data		Epigenetic and genetic data	Baseline	Mo/Fa/C	Case-control
Biobank Borealis	Finnish Maternity Cohort Biobank	Maternal first trimester serum sample	Baseline	Mo	Case-control

Mo, index mother; Fa, index father; C, index child; S, siblings of the index child; G, grandparents of the index child; OGTT, oral glucose tolerance test

^aYear when register was established.