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Table 1 Participants and measures

From: Do inattention and hyperactivity symptoms equal scholastic impairment? evidence from three European cohorts

  Sweden Denmark Finland
Initial data collection (years) 1992 – 1994 1990–1992 1985 – 1986
Initiated during gestational week 10 14 12
Geographic area Uppsala Aarhus Northern Finland
  County   (Oulu Lapland Provinces)
Inclusion criteria nulliparity + Scandinavian origin all pregnant women all pregnant women
Sample size    
   Mothers (% of eligible) 476 (91%) 8010 (98%) 9362 (99%)
   live births 411 8244 9432
Maternal age (Y, sd) 27.0 (4) 28.6(5) 27.8 (6)
Family structure at birth    
   cohabitated with expectant father 91% 95% 95%
Follow-up data collection 2001–2002 2001 1993–1994
Retained at follow-up 290 (74%) 5039 (61%) 9297 (99%)
Sample size:    
   Participating eligible teachers1 208 (96%) 4354 (85%) 8525 (92%)
Child age (years) 7–8 10–12 7–8
Child gender (% boys) 49% 51% 51%
Maternal education (%)    
   secondary 85.7 90.6 90.5
   college/university2 15.2 9.5 9.5
Family structure    
   two biological parents 78.1% 78.2% 87.8%
   disrupted family3 21.9% 21.8% 12.2%
Inattention & hyperactivity symptoms assessment SDQ4 SDQ4 CBQ5
Scholastic performance:    
   writing, reading, mathematics 7-pt scale 5-pt scale impaired/unimpaired
  1. 1 teachers' eligiblity was determined by parental consent
  2. 2 four or more years of college/university education or university degree
  3. 3 disrupted family encompassed single parent households and reconstructed family with step-parent
  4. 4 Strengths and Difficulties Questionnaire subscale for hyperactivity-inattention items: (nr. 2) restless, (nr. 10) fidgety, and (nr. 15) easily distracted
  5. 5 Children's Behaviour Questionnaire Rutter B2 subscale for hyperactivity-inattention items: (nr. 1) restless (nr. 3) squirmy, fidgety, and (nr. 16) not able to concentrate