Table 1. Characteristics of the Participants Included in the Study Samplea.
| Characteristic | No. (%) | P valueb | ||
|---|---|---|---|---|
| Total (N = 1623) | Females (n = 845) | Males (n = 778) | ||
| Low birth weight (<2500 g) | 49 (3.0) | 25 (3.0) | 24 (3.1) | .53 |
| Perceived difficult temperament, mean (SD)c | ||||
| Mother | 2.7 (1.6) | 2.7 (1.6) | 2.7 (1.6) | .70 |
| Missing | 7 (0.4) | 4 (0.5) | 3 (0.4) | |
| Father | 2.9 (1.5) | 2.8 (1.5) | 2.9 (1.5) | .23 |
| Missing | 244 (15.0) | 120 (14.2) | 124 (15.9) | |
| Positive interactions, mean (SD)d | 9.0 (1.1) | 9.0 (1.1) | 9.0 (1.0) | .48 |
| Missing | 2 (0.1) | 1 (0.1) | 1 (0.1) | |
| Family socioeconomic status, mean (SD)e | 0.1 (1.0) | 0.1 (1.0) | 0 (1.0) | .30 |
| Missing | 6 (0.4) | 3 (0.4) | 3 (0.4) | |
| Age at birth, mean (SD), y | ||||
| Mother | 29.4 (5.2) | 29.5 (5.1) | 29.3 (5.2) | .24 |
| Missing | 1 (0.1) | 0 | 1 (0.1) | |
| Father | 32.3 (5.5) | 32.1 (5.4) | 32.4 (5.6) | .40 |
| Missing | 116 (7.1) | 57 (6.7) | 59 (7.6) | |
| Family functioning score, mean (SD)f | 1.7 (1.4) | 1.7 (1.4) | 1.7 (1.5) | .91 |
| Missing | 11 (0.7) | 8 (0.9) | 3 (0.4) | |
| Nonintact family (single or blended) | 327 (20.1) | 176 (2.8) | 151 (19.4) | .55 |
| Missing | 3 (0.2) | 2 (0.2) | 1 (0.1) | |
| Maternal smoking during pregnancy | 401 (24.7) | 218 (25.8) | 183 (23.5) | .30 |
| Missing | 9 (0.6) | 5 (0.6) | 4 (0.5) | |
| Maternal mental health | ||||
| Depression, mean (SD)g | 1.4 (1.3) | 1.3 (1.3) | 1.4 (1.4) | .37 |
| Missing value | 6 (0.4) | 2 (0.2) | 4 (0.5) | |
| Antisociality in adolescence score, mean (SD)g | 0.8 (0.9) | 0.8 (0.9) | 0.9 (1.0) | .36 |
| Missing | 52 (3.20) | 24 (2.8) | 28 (3.6) | |
| Paternal mental health | ||||
| Depression, mean (SD)g | 1.0 (0.9) | 1.0 (0.9) | 1.0 (0.9) | .22 |
| Missing value | 228 (14.0) | 114 (13.5) | 114 (14.7) | |
| Antisociality in adolescence score, mean (SD)h | 0.7 (0.9) | 0.6 (0.9) | 0.7 (0.9) | .07 |
| Missing | 233 (14.4) | 113 (13.4) | 120 (15.4) | |
Variables were measured when the child was aged 5 months. Data were compiled from the final master file of the Québec Longitudinal Study of Child Development (1998-2018), Gouvernement du Québec, Institut de la Statistique du Québec.
Comparison of sex-specific samples; P values are based on a χ2 test of independence for categorical variables and on a Wilcoxon test for continuous variables.
Assessed with 7 items (eg, “How easy or difficult is it for you to calm or soothe your baby when he/she is upset?”) from the Infant Characteristics Questionnaire,32 administrated to both parents. Scores range from 0 to 10, with higher scores indicating more difficult temperament.
Assessed with 5 items from the Parent Practices Scale,33 evaluating positive interactions between the mother and the child. Scores ranges from 0 to 10, with higher scores indicating high positive interactions.
Assessed with an aggregate of 5 items regarding parental educational level, parental occupation, and annual gross income (range, −3 to 3, centered at 0, with higher scores indicating higher socioeconomic status).
Assessed with 7 items (eg, do not get along well together) from McMaster Family assessment administered to the mother (Ontario Child Health Study: Reliability and Validity of the General Functioning Subscale of the McMaster Family Assessment Device34). Scores range from 0 to 10, with higher scores indicating lower family functioning.
Assessed using a short version of the Centre for Epidemiological Study Depression Scale.35 Scores range from 0 to 10, with higher scores indicating higher depressive symptoms.
Assessed with binary questions on 5 different conduct problems based on the DSM-IV criteria for conduct disorder and antisocial personality disorder.36 Scores range from 0 to 5, with higher scores indicating more antisocial behaviors.