Table 3 Family factors, personal factors, parental factors and severe externalizing behaviors among school-aged boys with ADHD

Family factors

Birth order

First-born vs. Later-born

1.24 [1.03, 1.49]*

1.28 [1.04, 1.58]*

Family structure

Not with vs. with both-parents

1.70 [1.34, 2.14]***

1.35 [1.04, 1.74]*

Sibling status

Without vs. with siblings

1.21 [0.95, 1.53]

0.97 [0.74, 1.27]

Family history of mental disorders

Yes vs. no

1.36 [1.13, 1.63]***

1.31 [1.09, 1.58]**

Personal factors

Birth term

Preterm vs. full-term birth

1.29 [0.97, 1.72]

1.22 [0.88, 1.68]

Birth mode

Cesarean section vs.

normal spontaneous delivery

Deliv

0.88 [0.73, 1.06]

0.84 [0.69, 1.03]

Birth body weight

< 2500 vs. ≥2500 gm

1.28 [0.87, 1.87]

1.10 [0.72, 1.67]

Prenatal complication

Yes vs. no

1.33 [1.03, 1.70]*

1.33 [1.03, 1.73]*

Perinatal complication

Yes vs. no

1.21 [0.99, 1.49]

1.10 [0.88, 1.38]

Medical comorbidity

Yes vs. no

1.62 [1.27, 2.07]***

1.49 [1.15, 1.91]**

Psychiatric comorbidity

Yes vs. no

1.04 [0.87, 1.25]

1.01 [0.84, 1.22]

Parental factors

Paternal education level

> 12 vs. ≦12 years

0.63 [0.53, 0.76]***

0.72 [0.58, 0.91]**

Maternal education level

> 12 vs. ≦12years

0.68 [0.57, 0.83]

0.83 [0.66, 1.05]

Paternal occupational status

Yes vs. no

0.71 [0.44, 1.13]

0.81 [0.50, 1.31]

Maternal occupational status

Yes vs. no

1.13 [0.94, 1.37]

1.16 [0.95, 1.42]

Paternal age at childbirth

< 20 vs. ≥20 years

1.78 [0.54, 5.95]

1.71 [0.19, 2.71]

Maternal age at childbirth

< 20 vs. ≥20 years

2.29 [1.35, 3.87]**

1.78 [1.08, 3.21]*