Table 1. Birth and child/adolescent characteristics presented as means ± SD or n (%).
| Characteristic | Mean ± SD or n (%) | n | ||
| All | Male | Female | ||
| Birth outcomes | ||||
| Sex | 4596 (51.3) | 4358 (48.7) | 8954 | |
| Birth weight (g) | 3575±534 | 3638±537 | 3509±523 | 8954 |
| <2500 | 2044±449 | 2025±459 | 2059±441 | 248 |
| 2500–4499 | 3578±424 | 3626±420 | 3528±422 | 8388 |
| ≥4500 | 4704±194 | 4707±197 | 4697±190 | 318 |
| Gestational age at birth (weeks) | 39.4±1.6 | 39.4±1.6 | 39.5±1.6 | 8950 |
| Preterm birth (<37 weeks) | 34.4±2.3 | 34.4±2.3 | 34.3±2.3 | 366 |
| Term birth (≥37 weeks) | 39.6±1.2 | 40.0±1.2 | 40.0±1.2 | 8584 |
| Placental weight (g) | 646±132 | 652±133 | 640±131 | 8934 |
| <550 | 874 (48.6) | 924 (51.4) | 1798 | |
| 550–719 | 2425 (50.8) | 2349 (49.2) | 4774 | |
| ≥720 | 1287 (54.5) | 1075 (45.5) | 2362 | |
| Placental surface area (cm2) | 335±70 | 337±70 | 334±69 | 8821 |
| Placental-to-birth-weight ratio | 18.2+3.1 | 18.0±3.1 | 18.3±3.0 | 8934 |
| Behavioral outcomes | ||||
| 8-y-olds (teacher report) | ||||
| Rutter a | ||||
| Probable psychiatric disturbance | 1140 (14.1) | 801 (19.5) | 339 (8.6) | 8065 |
| Antisocial disorder | 725 (9.0) | 570 (13.9) | 155 (4.0) | 8065 |
| Neurotic disorder | 328 (4.1) | 171 (4.2) | 157 (4.0) | 8065 |
| Inattention-hyperactivity | 756 (9.4) | 576 (14.0) | 180 (4.5) | 8080 |
| Inattentionb | 1705 (21.1) | 1220 (30.0) | 485 (12.2) | 8088 |
| Hyperactivityc | 575 (7.1) | 468 (11.4) | 107 (2.7) | 8086 |
| 16-y-olds (parent report) | ||||
| SWAN a | ||||
| Combined ADHD | 349 (5.3) | 231 (7.0) | 118 (3.5) | 6607 |
| Inattentiond | 332 (5.1) | 230 (7.1) | 102 (3.1) | 6500 |
| Hyperactivity-impulsivitye | 306 (4.7) | 197 (6.1) | 109 (3.3) | 6467 |
a
assessment of symptoms based on fulfilment of criteria according to the Rutter B2/Strengths and Weaknesses of ADHD symptoms and Normal behavior (SWAN) scale.
b
assessment based on Rutter item number 16.
c
assessment based on sum of Rutter items 1 and 3.
d
SWAN subscale consisting of sum of 9 items.
e
SWAN subscale consisting of sum of 9 items.