Table 1.
Characteristics of the study sample
| Characteristics | Rural sample (N = 65 184) | Urban sample (N = 5359) |
|---|---|---|
| Height (cm, mean and SD) | 158.7 (4.5) | 159.2 (4.6) |
| Province of residence (%) | ||
| Hebei | 2.3 | 3.3 |
| Zhejiang | 86.4 | 81.1 |
| Jiangsu | 11.2 | 15.5 |
| Education (%) | ||
| no schooling | 5.3 | 4.3 |
| elementary school | 36.6 | 19.5 |
| junior high school | 50.3 | 48.1 |
| high school and above | 7.5 | 27.5 |
| missing | 0.3 | 0.7 |
| Ethnicity (%) | ||
| Han | 99.3 | 99.5 |
| minority | 0.6 | 0.5 |
| missing | 0.1 | 0.0 |
| Occupation (%) | ||
| farmer | 81.5 | 50.6 |
| worker | 16.7 | 33.8 |
| other | 1.7 | 15.1 |
| missing | 0.1 | 0.5 |
| Weight status (%) | ||
| underweight | 10.7 | 14.6 |
| normal weight | 79.3 | 77.8 |
| overweight | 8.2 | 6.4 |
| obese | 0.5 | 0.4 |
| missing | 1.4 | 0.7 |
| Hypertension (%) | ||
| no | 83.3 | 76.0 |
| yes | 15.9 | 23.1 |
| missing | 0.8 | 0.9 |
| Urine protein concentration (%) | ||
| negative | 75.3 | 79.1 |
| trace (5-20 mg/dl) | 4.9 | 6.1 |
| 1 + (30 mg/dl) | 1.3 | 1.5 |
| 2 + and above(>100mg/dl) | 0.2 | 0.2 |
| missing | 18.3 | 12.9 |
Source: the China-U.S.Collaborative Project for Neural Tube Birth Defect Prevention.