Table 1. Effects of risk factors on 25(OH)D and BMD.
| Variables | N (%) | 25(OH)D | BMD | Low BMD | |||
|---|---|---|---|---|---|---|---|
| Mean ± SD | P | Mean ± SD | P | N (%) | P | ||
| 25(OH)D quartiles (nmol/L) | |||||||
| ≤ 47.7 | 1134 (25.0) | 34.5 ± 9.8 | < 0.001 | 3336.3 ± 230.7 | < 0.001 | 294 (25.9) | < 0.001 |
| 47.8 - 62.9 | 1136 (25.1) | 55.1 ± 4.4 | 3404.9 ± 230.7 | 212 (18.7) | |||
| 63.0 - 78.0 | 1138 (25.1) | 70.2 ± 4.3 | 3383.7 ± 238.3 | 204 (17.9) | |||
| ≥ 78.1 | 1124 (24.8) | 95.5 ± 16.6 | 3399.8 ± 225.5 | 141 (12.5) | |||
| 25(OH)D concentrations | |||||||
| < 50 nmol/L | 1310 (28.9) | 36.4 ± 10.3 | < 0.001 | 3345.8 ± 231.7 | < 0.001 | 335 (25.6) | < 0.001 |
| 50–75 nmol/L | 1864 (41.1) | 62.2 ± 7.1 | 3397.7 ± 233.8 | 325 (17.4) | |||
| ≥ 75 nmol/L | 1358 (30.0) | 92.2 ± 16.7 | 3392.5 ± 229.1 | 191 (14.1) | |||
| Gender | |||||||
| Male | 2380 (52.5) | 65.2 ± 24.6 | < 0.001 | 3386.8 ± 236.2 | 0.087 | 444 (18.7) | 0.825 |
| Female | 2152 (47.5) | 62.2 ± 24.1 | 3374.9 ± 229.0 | 407 (18.9) | |||
| Age | |||||||
| 0–6 months | 413 (9.1) | 59.7 ± 23.9 | < 0.001 | 2991.0 ± 149.6 | < 0.001 | 65 (15.7) | 0.379 |
| 7–12 months | 436 (9.6) | 65.2 ± 25.1 | 3149.5 ± 124.2 | 73 (16.7) | |||
| 13–24 months | 804 (17.7) | 66.9 ± 24.1 | 3298.3 ± 170.4 | 143 (17.8) | |||
| 25–36 months | 696 (15.4) | 66.6 ± 24.2 | 3400.7 ± 182.0 | 134 (19.3) | |||
| 37–48 months | 738 (16.3) | 65.1 ± 24.2 | 3499.8 ± 145.8 | 146 (19.8) | |||
| 49–60 months | 749 (16.5) | 61.2 ± 24.5 | 3534.9 ± 133.9 | 149 (19.9) | |||
| ≥ 61 months | 696 (15.4) | 60.1 ± 23.9 | 3542.6 ± 151.9 | 141 (20.3) | |||
| Gestational age | |||||||
| Term infant | 4143 (94.8) | 63.7 ± 24.5 | 0.351 | 3379.9 ± 232.4 | 0.011 | 768 (18.5) | 0.053 |
| Preterm infant | 228 (5.2) | 62.2 ± 25.5 | 3334.6 ± 261.4 | 54 (23.7) | |||
| Gestational season | |||||||
| Spring | 1346 (29.7) | 60.6 ± 24.8 | < 0.001 | 3447.3 ± 222.1 | < 0.001 | 243 (18.1) | < 0.001 |
| Summer | 1810 (39.9) | 63.6 ± 26.8 | 3334.9 ± 229.8 | 276 (15.2) | |||
| Autumn | 580 (12.8) | 69.5 ± 21.8 | 3370.8 ± 239.5 | 139 (24.0) | |||
| Winter | 796 (17.6) | 65.2 ± 18.3 | 3381.9 ± 226.6 | 193 (24.2) | |||
| Delivery mode | |||||||
| Spontaneous delivery | 1913 (43.2) | 63.6 ± 25.3 | 0.502 | 3369.9 ± 238.7 | 0.003 | 391 (20.4) | 0.006 |
| Cesarean delivery | 2516 (56.8) | 64.1 ± 23.8 | 3390.7 ± 227.2 | 432 (17.2) | |||
| Birth weight | |||||||
| < 2500 g | 187 (4.2) | 65.2 ± 24.3 | 0.609 | 3364.7 ± 235.7 | 0.346 | 32 (17.1) | 0.787 |
| 2500–4000 g | 3903 (87.3) | 63.7 ± 24.6 | 3379.6 ± 232.9 | 733 (18.8) | |||
| ≥ 4000 g | 379 (8.5) | 63.0 ± 22.4 | 3393.7 ± 231.5 | 74 (19.5) | |||
| Feeding patterns | |||||||
| Breast feeding | 2339 (52.0) | 63.7 ± 24.8 | 0.179 | 3386.3 ± 233.5 | 0.073 | 441 (18.9) | 0.128 |
| Mixed feeding | 1308 (29.1) | 63.3 ± 22.7 | 3368.6 ± 233.0 | 259 (19.8) | |||
| Artificial feeding | 849 (18.9) | 65.2 ± 25.6 | 3385.5 ± 231.0 | 139 (16.4) | |||
| Milk intake during pregnancy | |||||||
| ≥ 250 ml/day | 1378 (34.0) | 65.0 ± 26.6 | 0.047 | 3366.1 ± 234.4 | 0.300 | 247 (17.9) | 0.359 |
| < 250 ml/day | 2679 (66.0) | 63.3 ± 23.4 | 3374.3 ± 239.9 | 512 (19.1) | |||
| VD or calcium supplementation during pregnancy | |||||||
| Yes | 1633 (39.9) | 64.8 ± 25.1 | 0.027 | 3380.7 ± 241.5 | 0.233 | 224 (13.7) | < 0.001 |
| No | 2464 (60.1) | 63.0 ± 23.6 | 3371.5 ± 238.3 | 538 (21.8) | |||
| Time of outdoor activity during pregnancy | |||||||
| < 1 h | 696 (17.7) | 61.5 ± 24.6 | < 0.001 | 3322.4 ± 247.1 | < 0.001 | 174 (25.0) | < 0.001 |
| 1–2 h | 1999 (51.0) | 63.0 ± 23.9 | 3364.9 ± 234.4 | 387 (19.4) | |||
| > 2 h | 1227 (31.3) | 66.3 ± 24.0 | 3388.5 ± 232.8 | 179 (14.6) | |||
| Milk intake for children | |||||||
| ≥ 250 ml/day | 2100 (53.8) | 64.9 ± 23.9 | 0.018 | 3374.3 ± 222.6 | 0.200 | 336 (16.0) | < 0.001 |
| < 250 ml/day | 1804 (46.2) | 63.1 ± 23.7 | 3384.1 ± 249.2 | 385 (21.3) | |||
| VD or calcium supplementation for children | |||||||
| Yes | 1971 (50.4) | 64.3 ± 24.4 | 0.025 | 3373.2 ± 249.9 | 0.684 | 291 (14.8) | < 0.001 |
| No | 1942 (49.6) | 62.6 ± 23.9 | 3376.3 ± 228.2 | 457 (23.5) | |||
| Time of outdoor activity for children | |||||||
| < 1 h | 435 (9.7) | 59.6 ± 20.9 | < 0.001 | 3231.7 ± 272.1 | < 0.001 | 116 (26.7) | < 0.001 |
| 1–2 h | 2014 (44.8) | 62.8 ± 24.2 | 3364.2 ± 236.7 | 435 (21.6) | |||
| > 2 h | 2042 (45.5) | 65.6 ± 25.0 | 3429.3 ± 202.6 | 290 (14.2) | |||