Table 1.
Demographic characteristics of study participants
| Variables | Value1 | N |
|---|---|---|
| Chronological age at 9-month assessment (days) | 279 ± 7 (267-309) | 71 |
| Gestational age (days) | 277 ± 7 (259-291) | 69 |
| Male gender (N) | 31 (43.7%) | 71 |
| Birth weight (grams) | 3,487 ± 426 (2,700-4,500) | 71 |
| Father's age (years) | 30.6 ± 4.3 (24-46) | 64 |
| Mother's age (years) | 28.4 ± 4.6 (21-46) | 68 |
| Father education greater than high school (N) | 19 (28.4%) | 67 |
| Mother education greater than high school (N) | 18 (25.4%) | 71 |
| Median number of family members in the household | 5 (3-9) | 71 |
| Median annual household income for those who live in rural areas2 | 30,000-50,000 RMB | 52 |
| Median annual household income for those who live in urban areas3 | 50,000-100,000 RMB | 16 |
1
Continuous variables are represented as mean ± SD (range) and ordinal variables as median. Dichotomous variables (gender, father and mother education) are shown as number and percentage (in parentheses).
2
Annual household income for those who live in rural areas consisted of a 6-point scale as follows: 1 = < 5 K, 2 = 5-10 K, 3 = 10-30 K, 4 = 30-50 K, 5 = 50-100 K, 6 = > 100 K (RMB/year)
3
Annual household income for those who live in urban areas consisted of a 6-point scale as follows: 1 = < 10 K, 2 = 10-30 K, 3 = 30-50 K, 4 = 50-100 K, 5 = 100-200 K, 6 = >200 K (RMB/year)