Table 1. Descriptive characteristics of the study population.
| Separated (n = 124) | Cohabiting (n = 2752) | P value a | |||
|---|---|---|---|---|---|
| Mean age; years (SD) | 11.3 | (0.7) | 11.1 | (0.7) | 0.05 |
| Gender; n (%) | |||||
| boys | 59 | (47.6) | 1358 | (49.3) | |
| girls | 65 | (52.4) | 1394 | (50.7) | 0.70 |
| Birth weight; n (%) | |||||
| < 2500 gram | 5 | (4.5) | 90 | (3.7) | |
| 2500–3249 gram | 36 | (32.1) | 604 | (24.9) | |
| 3250–4000 gram | 58 | (51.8) | 1,348 | (55.5) | |
| > 4000 gram | 13 | (11.6) | 385 | (15.9) | 0.27 |
| Gestational age; n (%): | |||||
| < 37 weeks | 5 | (4.4) | 110 | (4.2) | |
| ≥ 37 weeks | 108 | (95.6) | 2,479 | (95.8) | 0.93 |
| Mean maternal pre-pregnancy BMI; kg/m 2 (SD) | 21.9 | (4.0) | 21.7 | (3.2) | 0.42 |
| Maternal weight gain during pregnancy; n (%): | |||||
| < 5 kg | 2 | (1.9) | 27 | (1.2) | |
| 5–9 kg | 21 | (20.2) | 235 | (10.4) | |
| 10–14 kg | 39 | (37.5) | 932 | (41.2) | |
| 15–19 kg | 25 | (24.0) | 787 | (34.8) | |
| ≥ 20 kg | 17 | (16.4) | 279 | (12.4) | 0.01 |
| Maternal smoking during pregnancy; n (%): | |||||
| 0 cigarettes per day | 47 | (40.1) | 1918 | (70.9) | |
| 1–4 cigarettes per day | 7 | (6.0) | 121 | (4.5) | |
| 5–9 cigarettes per day | 14 | (12.0) | 246 | (9.1) | |
| 10–14 cigarettes per day | 20 | (17.1) | 264 | (9.7) | |
| ≥ 15 cigarettes per day | 29 | (24.8) | 156 | (5.8) | < 0.01 |
| Maternal educational level at child birth; n (%): | |||||
| ≤ 9 years | 43 | (48.9) | 617 | (25.9) | |
| 10–11 years | 14 | (15.9) | 751 | (31.5) | |
| ≥12 years | 31 | (35.2) | 1015 | (42.6) | <0.01 |
| Mean maternal age at child birth; years (SD) | 29.1 | (5.8) | 30.0 | (4.5) | 0.04 |
| Mean breast feeding; months (SD) | 4.2 | (2.5) | 4.2 | (2.1) | 0.94 |
| Parity; n (%): | |||||
| 0 | 72 | (58.1) | 1348 | (49.0) | |
| 1 | 35 | (28.2) | 998 | (36.3) | |
| ≥ 2 | 17.0 | (13.7) | 403 | (14.7) | 0.12 |
| Overweight children; n (%) | 27 | (21.8) | 357 | (13.0) | 0.01 |
| Obese children; n (%) | 6 | (4.8) | 44 | (1.6) | 0.01 |
Separate: Children whose biological parents lived separately before birth.
Cohabiting: Children whose biological parents lived together before birth.
SD standard deviation.
a Chi-square test.
BMI body mass index.