| Criteria | Classification | LBC (N = 469) | Non-LBC (N = 650) | Caregivers (N = 363) |
| 1. Sex | Male | 50.1% (n = 235) | 47.1% (n = 306) | 39.4% (n = 132) |
| Female | 49.9% (n = 234) | 52.9% (n = 344) | 60.6% (n = 203) | |
| 2. Age | Aged 9 - 11 | 48.6% (n = 227) | 48.8% (n = 312) | - |
| Aged 12 - 15 | 51.4% (n = 240) | 51.6% (n = 333) | - | |
| Mean (SD) | 11.70 (1.59) | 12.01 (1.68) | 56.60 (14.54) | |
| 3. Level of school | Primary school | 49.3% (n = 231) | 51.7% (n = 336) | - |
| Secondary school | 50.7% (n = 238) | 48.3% (n = 314) | - | |
| 4. Length of parental migration | ≤2 years | 39.0% (n = 139) | - | - |
| 2 - 5 years | 33.4% (n = 119) | - | - | |
| >5 years | 27.5% (n = 98) | - | - | |
| Mean (SD) | 4.24 (3.90) | - | - | |
| 5. Who works far away from home | Father | 39.4% (n = 176) | - | - |
| Mother | 23.5% (n = 105) | - | - | |
| Two parents | 37.1% (n = 166) | - | - | |
| 6. Residential area of children | Phu Tho | 23.9% (n = 112) | 123.4% (n = 152) | 22.6% (n = 82) |
| Bac Ninh | 32.8% (n = 154) | 34.2% (n = 222) | 28.7% (n = 104) | |
| Ha Nam | 43.3% (n = 203) | 42.5% (n = 276) | 48.8% (n = 177) | |
| 7. Relationship with LBC | Mother of LBC |
|
| 22.6% (n = 80) |
|
| Father of LBC | - | - | 12.4% (n = 45) |
|
| Grandmother/father | - | - | 61.0% (n = 216) |
|
| Relatives | - | - | 3.7% (n = 13) |
| 8. Have trouble with their health | Yes | - | - | 37.8% (n = 128) |
|
| No | - | - | 58.1% (n = 211 ) |