Appendix 1—table 2. Descriptive statistics of analytic sample (N=40,949)*, unimputed data.
| Continuous variables | mean | SD | N obs | |
|---|---|---|---|---|
| Maternal age at birth | 30.2 | 4.4 | 40,949 | |
| Paternal age at birth | 32.6 | 5.1 | 40,945 | |
| Maternal depressive/anxiety symptoms, based on 5 items from the Hopkins Symptoms Checklist-25 (SCL-25)† |
1.2 | 1.9 | 39,647 | |
| Paternal depressive/anxiety symptoms, based on 8 items from the Hopkins Symptoms Checklist-25 (SCL-25)‡ |
1.1 | 2.1 | 38,050 | |
| Maternal ADHD symptoms: adult ADHD self-report scale§ | 6.5 | 3.4 | 24,192 | |
| Paternal ADHD symptoms: adult ADHD self-report scale¶ | 8.2 | 3.1 | 16,348 | |
| Maternal pre-pregnancy BMI (kg/m2) | 24.0 | 4.1 | 39,323 | |
| Paternal BMI (kg/m2) | 25.9 | 3.2 | 39,405 | |
| Child’s BMI at age 8 (kg/m2) | 16.2 | 2.0 | 16,144 | |
| Child depressive symptoms age 8: Short Mood and Feelings Questionnaire (SMFQ)** | 1.8 | 2.4 | 18,747 | |
| Child anxiety symptoms age 8: Screen for Child Anxiety Related Disorders (SCARED)†† | 1.0 | 1.2 | 18,834 | |
| Child ADHD symptoms age 8: Parent/Teacher Rating Scale for Disruptive Behaviour Disorders (RS-DBD)‡ ‡ | 8.4 | 7.1 | 18,813 | |
| Child ADHD symptoms (inattention) age 8: Parent/Teacher Rating Scale for Disruptive Behaviour Disorders (RS-DBD)§ § | 4.9 | 4.0 | 18,794 | |
| Child ADHD symptoms (hyperactivity) age 8: Parent/Teacher Rating Scale for Disruptive Behaviour Disorders (RS-DBD)§ § | 3.5 | 3.8 | 18,787 | |
| Categorical variables | Category | % | N obs | |
| Child’s sex | male | 51.0 | 40,949 | |
| female | 48.9 | |||
| maternal educational qualifications | 9 year elementary education | 2.0 | 39,569 | |
| Up to 2 years further education | 4.1 | |||
| Further education: vocational | 12.1 | |||
| Further education: general studies, sixth form | 14.9 | |||
| Higher education: college/university, up to 4 years | 42.8 | |||
| Higher education: college/university, over 4 years | 24.8 | |||
| paternal educational qualifications | 9 year elementary education | 3.4 | 40,062 | |
| Up to 2 years further education | 5.6 | |||
| Further education: vocational | 25.1 | |||
| Further education: general studies, sixth form | 12.9 | |||
| Higher education: college/university, up to 4 years | 28.5 | |||
| Higher education: college/university, over 4 years | 24.4 | |||
| maternal parity at child’s birth | 0 | 46.8 | 40,949 | |
| 1 | 35.7 | |||
| 2 | 14.0 | |||
| 3 | 2.7 | |||
| 4+ | 0.7 | |||
| Mother’s marital status at birth | Married/registered partner | 97.4 | 40,949 | |
| single | 2.6 | |||
| Mother’s smoked during pregnancy | never | 51.1 | 40,118 | |
| Stopped before week 17 | 42.0 | |||
| Currently, sometimes | 2.4 | |||
| Currently, daily | 4.5 | |||
*
The reasons for exclusions and numbers in each case are shown in Appendix 1—figure 1.
†
Possible range: 0–15.
‡
Possible range: 0–24.
§
Possible range: 0–24.
¶
Possible range: 0–24.
**
Possible range: 0-26.
††
Possible range: 0–10.
‡ ‡
Possible range: 0–54.
§ §
Possible range: 0–27.