Table 1.
Main characteristics of mother–child pairs in the analysis population.
| Characteristic | All (% or mean ± SD) | Girlsª (% or mean ± SD) | Boysª (% or mean ± SD) |
|---|---|---|---|
| Child characteristics | |||
| From birth to 6 months of age | n = 391 | n = 186 | n = 205 |
| Gestational age (weeks) | 39.7 ± 1.4 | ||
| Birth weight (g) | 3,264 ± 394 | 3,202 ± 403 | 3,322 ± 378 |
| Birth weight z-score (SD) | –0.1 ± 0.8 | ||
| Birth length (cm) | 49.4 ± 1.8 | 49.0 ± 1.8 | 49.8 ± 1.9 |
| Weight at 6 months (g) | 7,654 ± 860 | 7,337 ± 776 | 7,937 ± 833 |
| Weight z-score at 6 months (SD) | –0.06 ± 0.9 | ||
| Weight gain z-score 0–6 months (SD) | 0.05 ± 0.1 | ||
| Rapid growth 0–6 months, yes (%) | 25 | 23 | 27 |
| Exclusive breastfeeding ≥ 16 weeks (%) | 49 | ||
| At 1 year of age | n = 377 | n = 178 | n = 199 |
| Exact age (months) | 14.5 ± 0.7 | ||
| Weight (kg) | 10.3 ± 1.2 | 9.9 ± 1.1 | 10.6 ± 1.1 |
| Length (cm) | 77.5 ± 2.8 | 76.8 ± 2.8 | 78.2 ± 2.7 |
| BMI z-score (SD) | 0.5 ± 0.9 | 0.5 ± 0.8 | 0.6 ± 0.9 |
| BMI z-score ≥ 85th percentile (%) | 27 | 23 | 30 |
| At 4 years of age | n = 370 | n = 176 | n = 194 |
| Exact age (months) | 53.3 ± 2.1 | ||
| Weight (kg) | 18.1 ± 2.8 | 17.8 ± 2.8 | 18.4 ± 2.8 |
| Height (cm) | 106 ± 4.5 | 105 ± 4.7 | 106 ± 4.2 |
| BMI z-score (SD) | 0.51 ± 1.0 | 0.37 ± 0.9 | 0.63 ± 1.1 |
| BMI z-score ≥ 85th percentile (%) | 22 | 19 | 25 |
| Waist circumference (cm)b | 52 ± 5.1 | ||
| Waist-to-height ratiob | 0.49 ± 0.04 | ||
| Waist-to-height ratio > 0.50 (%)b | 33 | 35 | 31 |
| Systolic BP (mmHg)c | 101 ± 12 | 100 ± 12 | 102 ± 12 |
| Diastolic BP (mmHg)c | 65 ± 12 | 64 ± 10 | 66 ± 13 |
| At 7 years of age | n = 360 | n = 171 | n = 189 |
| Exact age (months) | 82 ± 4.9 | ||
| Weight (kg) | 25.1 ± 5.2 | 24.6 ± 5.3 | 25.4 ± 5.1 |
| Height (cm) | 121 ± 5.8 | 121 ± 5.9 | 122 ± 5.6 |
| BMI z-score (SD) | 0.68 ± 1.2 | 0.57 ± 1.1 | 0.78 ± 1.3 |
| BMI z-score ≥ 85th percentile (%) | 29 | 26 | 32 |
| Waist circumference (cm) | 57.6 ± 6.8 | ||
| Waist-to-height ratio | 0.47 ± 0.05 | ||
| Waist-to-height ratio > 0.50 (%) | 21 | 22 | 21 |
| Systolic BP (mmHg)d | 105 ± 10 | 104 ± 11 | 106 ± 10 |
| Diastolic BP (mmHg)d | 63 ± 10 | 63 ± 11 | 62 ± 8 |
| Maternal characteristics | n = 391 | ||
| Country of origin (%) | |||
| Spain | 93 | ||
| Other | 6 | ||
| Missing | 1 | ||
| Age at delivery (years) | 30.6 ± 4.0 | ||
| Education (%) | |||
| Primary | 22 | ||
| Secondary | 43 | ||
| University | 35 | ||
| Social class (ISCO-88 code) (%) | |||
| Professionals, managers (I, II) | 24 | ||
| Other nonmanual (III) | 32 | ||
| Skilled, semiskilled, unskilled manual (IV, V) | 44 | ||
| Parity, nulliparous (%) | 56 | ||
| Prepregnancy BMI (kg/m2) | 23.7 ± 4.6 | ||
| Smoking (%) | |||
| Never/stopped before pregnancy | 73 | ||
| Yes, until 1st pregnancy trimester | 13 | ||
| Yes, throughout pregnancy | 14 | ||
| aCharacteristics that differ according to sex (p ≤ 0.20) are shown separately for girls and boys. Chi-square test was used to test for categorical variables, and t-test for continuous variables (all continuous variables normally distributed). bn = 366 (174 girls, 192 boys) due to missing numbers in the waist circumference covariate. cn = 342 (169 girls, 173 boys) due to missing numbers in the BP covariates. dn = 355 (170 girls, 185 boys) due to missing numbers in the BP covariates. | |||