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. 2020 Aug 18;17(8):e1003213. doi: 10.1371/journal.pmed.1003213

Table 1. Study population characteristics.

Characteristic All n = 620 Urban n = 236 Suburban n = 128 Rural n = 256
Sex, male 312 (50.3) 114 (48.3) 71 (55.5) 127 (49.6)
Birth year 1,986 ± 2.8 1,987 ± 2.7 1,987 ± 2.5 1,986 ± 2.9
Zygosity-chorionicity
    Dizygotic-dichorionic 356 (57.4) 150 (63.6) 74 (57.8) 132 (51.6)
    Monozygotic-dichorionic 106 (17.1) 40 (16.9) 14 (10.9) 52 (20.3)
    Monozygotic-monochorionic 158 (25.5) 46 (19.5) 40 (31.3) 72 (28.1)
Parental education
    Low 120 (38.7) 41 (34.8) 4 (6.3) 59 (46.1)
    High 190 (61.3) 77 (65.2) 44 (68.8) 69 (53.9)
Neighborhood income, euro 18,831 ± 2,481 18,898 ± 2,426 19,755 ± 2,848 18,308 ± 2,196
Intelligence (WISC-R) n = 620 n = 236 n = 128 n = 256
Age at investigation 11.0 ± 1.8 11.0 ± 1.7 10.9 ± 1.7 11.1 ± 1.9
Year of investigation 1,998 ± 1.6 1,998 ± 1.4 1,998 ± 1.6 1,998 ± 1.7
Intelligence score (IQ)
    Total 105.3± 14.2 106.2 ± 13.2 104.8 ± 14.2 104.8 ± 15.1
    Verbal 106.2 ± 13.5 107.0 ± 12.9 106.1± 13.3 105.5 ± 14.2
    Performance 103.2 ± 15.2 103.9 ± 14.1 102.4 ± 15.7 103.0 ± 15.9
Behavior (CBCL) n = 442 n = 168 n = 92 n = 182
Age at investigation 8.5 ± 2.2 8.4 ± 2.2 8.1 ± 2.0 8.7 ± 2.3
Year of investigation 1,994 ± 0.5 1,994 ± 0.5 1,994 ± 0.5 1,994 ± 0.5
CBCL score
    Total 46.5 ± 9.9 47.0 ± 9.5 46.8 ± 9.7 45.9 ± 10.3
    Externalizing 46.3 ± 9.9 47.2 ± 9.6 46.2 ± 10.1 45.4 ± 10.1
    Internalizing 47.7 ± 9.4 48.0 ± 9.4 48.2 ± 9.4 47.0 ± 9.4

Data presented are means ± standard deviation or number (percentage).

CLBL, Child Behavior Checklist; WISC-R, Wechsler Intelligence Scale for Children-Revised.