TABLE 2.
Characteristics of children included in the study (N = 3,770)1
| Child characteristics | Value | Missing (N, %) |
|---|---|---|
| Season of birth, N, % | 1,311 (34.8) | |
| spring | 731 (19.4) | |
| summer | 703 (18.6) | |
| autumn | 511 (13.6) | |
| winter | 514 (13.6) | |
| 25(OH)D concentration (nmol/L) at birth | 30.7 (5.4–81.9) | 1,311 (34.8) |
| Severely deficient (<25.0), N, % | 975 (25.9) | |
| Deficient (25.0–49.9), N, % | 932 (24.7) | |
| Sufficient (50.0–74.9), N, % | 444 (11.8) | |
| Optimal (≥75.0), N, % | 108 (2.9) | |
| Gender (N, %) | – | |
| Boys | 1,873 (49.7) | |
| Girls | 1,897 (50.3) | |
| Chronological age, y | 9.81 ± 0.35 | – |
| Ethnicity, N, % | 60 (1.6) | |
| Dutch | 2,221 (58.9) | |
| Cape Verdean | 112 (3.0) | |
| Dutch Antillean | 107 (2.8) | |
| Moroccan | 207 (5.5) | |
| Turkish | 242 (6.4) | |
| Surinamese | 263 (7.0) | |
| Other | 558 (14.8) | |
| Weight, kg | 34.00 (25.2–54.1) | – |
| Height, cm | 141.72 ± 6.75 | – |
| BMI, kg/m2 | 16.99 (14.0–24.7) | – |
| 25(OH)D, nmol/L | 66.20 (21.1–136.9) | 1536 (40.7) |
| Bone mineral density of head, g/cm2 | 1.35 (1.1–1.6) | 333 (8.8) |
| Dental age, y | 10.34 ± 0.83 | – |
| Stage of development for the central incisor | 8 (8–8) | – |
| Stage of development for the lateral incisor | 8 (7–8) | – |
| Stage of development for the canine | 6 (5–8) | – |
| Stage of development for the first premolar | 6 (5–7) | – |
| Stage of development for the second premolar | 6 (4–7) | – |
| Stage of development for the first molar | 8 (7–8) | – |
| Stage of development for the second molar | 6 (4–7) | – |
| Hypodontia, N, % | 197 (5.2) | – |
| Dental anomalies of position, N, % | 102 (2.7) |
1
Values are percentages for categorical variables, means ± SD for continuous variables with a normal distribution, or medians (95% range) for continuous variables with a skewed distribution from the original data. 25(OH)D, 25-hydroxyvitamin D.