Table 1 Characteristics of 1277 study population stratified by bone mineral density level.
Variable | NB (n = 1231) | IB (n = 46) | Total (n = 1277) | χ2/Z | P |
|---|---|---|---|---|---|
Age, years | 26.869 | < 0.001 | |||
3 | 148 (12.0) | 4 (8.7) | 152 (11.9) | ||
4 | 332 (27.0) | 3 (6.5) | 335 (26.2) | ||
5 | 505 (41.0) | 16 (34.8) | 521 (40.8) | ||
6 | 246 (20.0) | 23 (50.0) | 269 (21.1) | ||
Gender | 0.112 | 0.738 | |||
Boys | 673 (54.7) | 24 (52.2) | 1231 (96.4) | ||
Girls | 558 (45.3) | 22 (47.8) | 46 (3.6) | ||
Residency | 0.468 | 0.494 | |||
Urban | 1083 (88.0) | 42 (91.3) | 1125 (88.1) | ||
Rural | 148 (12.0) | 4 (8.7) | 152 (11.9) | ||
Left-behind children | 0.328 | 0.567 | |||
Yes | 257 (20.9) | 8 (17.4) | 265 (20.8) | ||
No | 974 (79.1) | 38 (82.6) | 1012 (79.2) | ||
Only child | 0.104 | 0.747 | |||
Yes | 348 (28.3) | 12 (26.1) | 360 (28.2) | ||
No | 883 (71.7) | 34 (73.9) | 917 (71.8) | ||
Current carer | 0.084 | 0.772 | |||
Parents | 1113 (90.4) | 41 (89.1) | 1154 (90.4) | ||
Others | 118 (9.6) | 5 (10.9) | 123 (9.6) | ||
Family monthly income | 0.156 | 0.692 | |||
<￥10,000 | 579 (47.0) | 23 (50.0) | 602 (47.1) | ||
≥￥10,000 | 652 (53.0) | 23 (50.0) | 675 (52.9) | ||
Father’s education level | 1.053 | 0.591 | |||
Primary school or below | 377 (30.6) | 16 (34.8) | 393 (30.8) | ||
Junior high school or high school | 416 (33.8) | 17 (37.0) | 433 (33.9) | ||
College or above | 438 (35.6) | 13 (28.3) | 451 (35.3) | ||
Mother’s education level | 1.202 | 0.548 | |||
Primary school or below | 428 (34.8) | 15 (32.6) | 443 (34.7) | ||
Junior high school or high school | 390 (31.7) | 18 (39.1) | 408 (31.9) | ||
College or above | 413 (33.5) | 13 (28.3) | 426 (33.4) | ||
Father working outside the home area | 0.447 | 0.504 | |||
Yes | 475 (38.6) | 20 (43.5) | 495 (38.8) | ||
No | 756 (61.4) | 26 (56.5) | 782 (61.2) | ||
Mother working outside the home area | 7.598 | 0.006 | |||
Yes | 402 (32.7) | 24 (52.2) | 426 (33.4) | ||
No | 829 (67.3) | 22 (47.8) | 851 (66.6) | ||
Weight Status | 0.968 | 0.809 | |||
Normal | 965 (78.4) | 34 (73.9) | 999 (78.2) | ||
Obesity | 81 (6.6) | 3 (6.5) | 84 (6.9) | ||
Overweight | 181 (14.7) | 9 (19.6) | 190 (14.9) | ||
Underweight | 4 (0.3) | 0 (0) | 4 (0.3) | ||
Head circumference, cm | 50.8 (49.6, 52.0) | 51.3 (50.0, 52.1) | 50.8 (49.7, 52.0) | −1.863 | 0.063 |
Chest circumference, cm | 55.5 (53.0, 58.5) | 58 (55.9, 61.6) | 56 (53.0, 58.5) | −4.188 | < 0.001 |
Waist circumference, cm | 54.5 (51.5, 58.0) | 56.0 (53.8, 62.0) | 54.5 (51.5, 58.0) | −2.783 | 0.005 |
Hip circumference, cm | 61.0 (58.0, 65.0) | 64.3 (61.6, 68.3) | 61 (58, 65) | −3.867 | < 0.001 |
