Baseline characteristics of the samples at recruitment and at the endpoint
| Variables | At recruitment (N=2220) | At endpoint (N=1178) | ||
| n (%) | Mean (SD) | n (%) | Mean (SD) | |
| Boys | 1155 (52.0) | 611 (51.9) | ||
| Single-child family | 1937 (87.3) | 1032 (87.6) | ||
| Birth weight (g) | 3334 (419) | 3325 (424) | ||
| Low birth weight | 34 (1.5) | 20 (1.7) | ||
| Normal birth weight | 2028 (91.4) | 1078 (91.5) | ||
| Macrosomia | 158 (7.1) | 80 (6.8) | ||
| Maternal age at childbirth (years) | 2217 | 28.4 (3.8) | 1176 | 28.6 (3.8) |
| Paternal age at childbirth (years) | 2211 | 31.1 (4.7) | 1172 | 31.3 (4.8) |
| Maternal prepregnancy BMI (kg/m2) | 2215 | 20.4 (2.6)* | 1174 | 20.4 (2.6) |
| Maternal underweight | 541 (24.4) | 487 (22.8) | ||
| Maternal normal weight | 194 (66.9) | 1463 (68.5) | ||
| Maternal overweight/obesity | 194 (8.8) | 187 (8.8) | ||
| Paternal BMI at recruitment (kg/m2) | 2201 | 23.5 (3.3)* | 1169 | 23.6 (3.4) |
| Paternal underweight | 87 (4.0) | 81 (3.8) | ||
| Paternal normal weight | 1232 (55.9) | 1169 (55.0) | ||
| Paternal overweight/obesity | 884 (40.1) | 877 (41.2) | ||
| Gestational weight gain | 2205 | 17.1 (5.4) | 1168 | 17.2 (5.6) |
| Gestational age at birth | 2206 | 39.5 (1.5) | 1162 | 39.5 (1.5) |
| Preterm | 80 (3.6) | 47 (4.0) | ||
| Full term | 2126 (96.4) | 1115 (96.0) | ||
| Delivery mode | ||||
| Vaginal | 699 (31.5) | 376 (31.9) | ||
| C-section | 1521 (68.5) | 802 (68.1) | ||
| Maternal pregnancy hypertension | 52 (2.6) | 30 (2.7) | ||
| Pregnancy smoking | 15 (0.7) | 8 (0.8) | ||
| Pregnancy secondhand smoking | 435 (19.9) | 240 (20.7) | ||
| Pregnancy alcohol consumption | 35 (1.6) | 20 (1.7) | ||
| Maternal educational level | ||||
| Middle school or less | 432 (19.5) | 227 (19.3) | ||
| High school/technical | 584 (26.3) | 321 (27.3) | ||
| University/college | 1117 (50.3) | 582 (49.4) | ||
| Master degrees or advanced | 87 (3.9) | 48 (4.1) | ||
| Paternal educational level | ||||
| Middle school or less | 343 (15.5) | 180 (15.3) | ||
| High school/technical | 644 (29.0) | 329 (27.9) | ||
| University/college | 1105 (49.8) | 595 (50.5) | ||
| Master degrees or advanced | 128 (5.8) | 74 (6.3) | ||
| Feeding pattern at the first month | ||||
| Exclusive breast feeding | 759 (36.7) | 418 (37.1) | ||
| Mixed feeding | 1015 (49.1) | 532 (48.2) | ||
| Formula feeding | 295 (14.3) | 153 (13.9) | ||
*BMI is presented as median (IQR).
BMI, body mass index; C-section, caesarean section.