Table 3 Bivariate linear associations between studied variables and mental-health indicators

Age

0.46 (0.3; 0.6)**

0.08 (− 0.1; 0.2)

0.26 (0.1; 0.4)**

0.14 (0.01; 0.26)*

−0.03 (− 0.1; 0.0)

−1.41 (−2.0; − 0.9)**

−1.80 (−2.7; − 0.9)**

Sex (Ref. Boys)

1.14 (0.7; 1.6)**

1.24 (0.8; 1.6)**

0.82 (0.4; 1.2)**

1.47 (1.11; 1.82)**

− 0.06 (− 0.2; 0.1)

−6.44 (− 7.8; − 5.0)**

−5.24 (− 7.8; − 2.7)**

Location (Ref. Rural)

1.48 (0.8; 2.1)**

1.37 (0.8; 1.9)**

0.07 (− 0.5; 0.6)

0.27 (− 0.22; 0.75)

− 0.05 (− 0.2; 0.1)

−1.61 (− 3.6; 0.3)

− 4.41 (− 7.8; − 1.0)*

Overweight (Ref. Normal)

0.30 (− 0.4; 1.0)

0.24 (− 0.3; 0.8)

0.05 (− 0.5; 0.6)

0.48 (− 0.01; 0.98)

0.07 (− 0.1; 0.2)

− 0.53 (− 2.5; 1.5)

−3.51 (− 7.0; − 0.0)*

Family Affluence Scale (tertiles)

−0.12 (− 0.4; 0.2)

0.22 (− 0.0; 0.5)

0.08 (− 0.2; 0.3)

−0.10 (− 0.34; 0.13)

−0.03 (− 0.1; 0.1)

0.99 (0.0; 1.9)*

0.57 (− 1.1; 2.3)

Family structure (Ref. Other)

−0.98 (− 2.0; 0.0)

−0.83 (− 1.6; − 0.0)*

−0.35 (− 1.2; 0.5)

−0.57 (− 1.3; 0.2)

0.21 (− 0.7; 0.5)

1.95 (− 1.1; 5.0)

− 1.02 (− 6.4; 4.3)

−1.61 (− 2.5; − 0.7)**

− 0.57 (− 1.3; 0.2)

− 0.58 (− 1.4; 0.2)

− 0.57 (− 1.3; 0.1)

0.11 (− 0.1; 0.4)

3.20 (0.4; 6.0)*

0.66 (−4.3; 5.6)

Family Apgar score

−0.13 (− 0.2; − 0.1)**

−0.22 (− 0.3; − 0.2)**

−0.15 (− 0.2; − 0.1)**

−0.14 (− 0.2; − 0.1)**

0.09 (0.1; 0.1)*

1.26 (1.1; 1.4)**

1.83 (1.5; 2.1)**

Physical Fitness (z-score)

−0.74 (− 1.1; − 0.4)**

−0.25 (− 0.6; 0.1)

−0.11 (− 0.4; 0.2)

−0.48 (− 0.8; − 0.2)**

0.06 (− 0.0; 0.2)

1.94 (0.8; 3.1)**

1.41 (− 0.6; 3.4)

Physical activity score

−0.43 (− 0.7; − 0.1)**

−0.61 (− 0.9; − 0.4)**

−0.63 (− 0.9; − 0.4)**

−0.70 (− 0.9; − 0.5)**

0.20 (0.11; 0.3)**

5.56 (4.7; 6.4)**

7.11 (5.6; 8.6)**

Screen time (hours per day)

0.09 (0.0; 0.1)**

0.06 (0.0; 0.1)**

−0.02 (− 0.1; 0.0)

0.03 (− 0.0; 0.1)

0.00 (− 0.0; 0.0)

−0.05 (− 0.2; 0.1)

−0.09 (− 0.4; 0.2)