Table 2 Family factors, personal factors, parental factors, and severe internalizing behaviors among school-aged boys with ADHD

Family factors

Birth order

First- vs. later-born

1.41 [1.18, 1.71]***

1.45 [1.17, 1.79]***

Family structure

Not with vs. with both-parents

1.43 [1.11, 1.87]**

1.30 [1.03, 1.46]*

Sibling status

Without vs. with siblings

1.16 [0.92, 1.47]

0.94 [0.73, 1.23]

Family history of mental disorders

Yes vs. no

1.34 [1.11, 1.61]**

1.26 [1.04, 1.53]*

Personal factors

Birth term

Preterm vs. full-term birth

1.14 [0.86, 1.52]

0.93 [0.61, 1.42]

Birth mode

Cesarean section vs.

normal spontaneous delivery

1.09 [0.90, 1.32]

1.05 [0.86, 1.28]

Birth body weight

< 2500 vs. ≥2500 g

1.15 [0.79, 1.68]

0.93 [0.61, 1.42]

Prenatal complication

Yes vs. no

1.81 [1.41, 2.32]***

1.72 [1.33, 2.22]***

Perinatal complication

Yes vs. no

1.53 [1.25, 1.88]***

1.42 [1.14, 1.78]**

Medical comorbidity

Yes vs. no

1.67 [1.31, 2.13]***

1.51 [1.18, 1.94]***

Psychiatric comorbidity

Yes vs. no

1.48 [1.23,1.78]***

1.49 [1.23, 1.81]***

Parental factors

Paternal education level

> 12 vs. ≤ 12 years

0.99 [0.83, 1.20]

0.96 [0.76, 1.20]

Maternal education level

> 12 vs. ≤ 12years

1.05 [0.87, 1.27]

1.07 [0.84, 1.35]

Paternal occupational status

Yes vs. no

1.48 [0.92, 2.39]

1.59 [0.97, 2.61]

Maternal occupational status

Yes vs. no

0.98 [0.81, 1.19]

0.99 [0.81, 1.21]

Paternal age at childbirth

< 20 vs. ≥20 years

2.55 [0.77, 8.50]

1.62 [0.44, 6.03]

Maternal age at childbirth

< 20 vs. ≥20 years

1.53 [0.95, 2.47]

1.30 [0.76, 2.24]