Table 3. Demographic and behavioral characteristics by BMI-for-age groups using WHO Z-core criteria.
| BMI-for-age group | Thin | Normal | Overweight | Obesity | p-value |
|---|---|---|---|---|---|
| n(%) | 216 (7.7) | 1848 (66.3) | 484 (17.4) | 240 (8.6) | |
| Age group | 216 (100) | 1848 (100) | 484 (100) | 240 (100) | |
| 11 years old, n (%) | 68 (31.5) | 433 (23.4) | 130 (26.9) | 83 (34.6) | <0.001 a |
| 12 years old, n (%) | 48 (22.2) | 450 (24.4) | 132 (27.3) | 77 (32.1) | |
| 13 years old, n (%) | 51 (23.6) | 512 (27.7) | 129 (26.7) | 37 (15.4) | |
| 14 years old, n (%) | 49 (22.7) | 453 (24.5) | 93 (19.2) | 43 (17.9) | |
| Sex | 216 (100) | 1848 (100) | 484 (100) | 240 (100) | |
| Boys, n (%) | 121 (56.0) | 825 (44.6) | 271 (56.0) | 181 (75.4) | <0.001 a |
| Girls, n (%) | 95 (44.0) | 1023 (55.4) | 213 (44.0) | 59 (24.6) | |
| Region | 216 (100) | 1848 (100) | 484 (100) | 240 (100) | |
| North, n (%) | 60 (27.8) | 668 (36.1) | 149 (30.8) | 50 (20.8) | <0.001 a |
| Center, n (%) | 96 (44.4) | 635 (34.4) | 140 (28.9) | 57 (23.8) | |
| South, n (%) | 60 (27.8) | 545 (29.5) | 195 (40.3) | 133 (55.4) | |
| Residency status | 216 (100) | 1848 (100) | 484 (100) | 240 (100) | |
| Urban, n (%) | 63 (29.2) | 711 (38.5) | 239 (49.4) | 129 (53.8) | <0.001 a |
| Rural, n (%) | 153 (70.8) | 1137 (61.5) | 245 (50.6) | 111 (46.3) | |
| Ethnicity | 216 (100) | 1845 (100) | 483 (100) | 240 (100) | |
| Kinh, n (%) | 169 (78.2) | 1504 (81.5) | 449 (93.0) | 219 (91.3) | <0.001 a |
| Other, n (%) | 47 (21.8) | 341 (18.5) | 34 (7.0) | 21 (8.8) | |
| Mother's BMI | 193 (100) | 1679 (100) | 446 (100) | 226 (100) | |
| Mean (SD) | 21.35 (2.51) | 21.77 (2.78) | 22.49 (3.29) | 22.96 (3.19) | <0.001 b |
| Median (IQI) | 20.83 (19.74; 22.49) |
21.56 (20.00; 23.11) |
22.06 (20.81; 23.73) |
22.53 (20.83; 24.56) |
<0.001 c |
| Normal, n (%) | 154 (79.8) | 1229 (73.2) | 298 (66.8) | 130 (57.5) | <0.001 a |
| Overweight, n (%) | 24 (12.4) | 294 (17.5) | 91 (20.4) | 51 (22.6) | |
| Obese, n (%) | 15 (7.8) | 156 (9.3) | 57 (12.8) | 45 (19.9) | |
| Father's BMI | 183 (100) | 1607 (100) | 428 (100) | 220 (100) | |
| Mean (SD) | 22.25 (4.36) | 22.53 (2.78) | 23.32 (2.52) | 23.80 (3.24) | <0.001 b |
| Median (IQI) | 22.04 (19.95; 23.66) |
22.50 (20.76; 24.22) |
23.51 (21.71; 24.80) |
23.71 (22.04; 25.10) |
<0.001 c |
| Normal, n (%) | 121 (66.1) | 924 (57.5) | 184 (43.0) | 90 (40.9) | <0.001 a |
| Overweight, n (%) | 41 (22.4) | 433 (26.9) | 150 (35.0) | 73 (33.2) | |
| Obese, n (%) | 21 (11.5) | 250 (15.6) | 94 (22.0) | 57 (25.9) | |
| Do at least a type of sport | 213 (100) | 1826 (100) | 481 (100) | 240 (100) | |
| No, n (%) | 16 (7.5) | 171 (9.4) | 46 (9.6) | 17 (7.1) | 0.55 a |
| Yes, n (%) | 197 (92.5) | 1655 (90.6) | 435 (90.4) | 223 (92.9) | |
| Physical mins per day, mean (SD) | 49.74 (27.47) | 52.43 (33.86) | 58.61 (34.33) | 66.28 (43.04) | <0.001 b |
| Play video games per day | 214 (100) | 1839 (100) | 483 (100) | 240 (100) | |
| No gaming, n (%) | 115 (53.7) | 887 (48.2) | 203 (42.0) | 73 (30.4) | <0.001 a |
| < = 1hour, n (%) | 44 (20.6) | 342 (18.6) | 93 (19.3) | 53 (22.1) | |
| 1 hour, n (%) | 28 (13.1) | 362 (19.7) | 105 (21.7) | 58 (24.2) | |
| 2 hours, n (%) | 18 (8.4) | 171 (9.3) | 66 (13.7) | 40 (16.7) | |
| 3 hours, n (%) | 6 (2.8) | 47 (2.6) | 12 (2.5) | 11 (4.6) | |
| ≥4 hours, n (%) | 3 (1.4) | 30 (1.6) | 4 (0.8) | 5 (2.1) | |
| Watching TV per day | 212(100) | 1833 (100) | 480 (100) | 239 (100) | |
| No watching, n (%) | 17 (8.0) | 103 (5.6) | 18 (3.8) | 10 (4.2) | 0.18 a |
| < = 1hour, n (%) | 48 (22.6) | 472 (25.8) | 137 (28.5) | 59 (24.7) | |
| 1 hour, n (%) | 85 (40.1) | 678 (37.0) | 176 (36.7) | 84 (35.1) | |
| 2 hours, n (%) | 52 (24.5) | 432 (23.6) | 105 (21.9) | 59 (24.7) | |
| 3 hours, n (%) | 6 (2.8) | 102 (5.6) | 24 (5.0) | 17 (7.1) | |
| ≥4 hours, n (%) | 4 (1.9) | 46 (2.5) | 20 (4.2) | 10 (4.2) |
Bold p-value indicates statistical significance (p < 0.05)
†Sample size for individual characteristics may not equal total due to missing values
* Children are defined as thinness if their weight-to-height was less than (-2SD), and normal if their weight-to-height was between (-2SD) and 1SD.
# equivalent to 23–25 kg/m2 for the overweight group and ≥ 25 kg/m2 for obesity
a p-value is obtained from Pearson’s chi-square test
b p-value was obtained from one-way ANOVA test
c p-value was obtained from Kruskal-Wallis test