Table 1.
Baseline characteristics of infants and their mothers in Changsha, China, 2013–2014.
| Variable | Sample Size (n) | Percentage (%) |
|---|---|---|
| Maternal education level | ||
| Junior high or inferior | 23 | 4.4 |
| Senior high | 105 | 20.2 |
| Bachelor’s degree | 339 | 65.3 |
| Master’s degree or advanced | 52 | 10.1 |
| Maternal age | ||
| <25 | 61 | 11.8 |
| 25–29 | 194 | 37.4 |
| 30–34 | 210 | 40.5 |
| ≥35 | 54 | 10.3 |
| Per capita income of Chinese households (yuan) | ||
| <5000 | 280 | 54.0 |
| 5001–<10,000 | 183 | 35.3 |
| 10,001–<15,000 | 41 | 7.9 |
| ≥15,000 | 15 | 2.9 |
| Marital status | ||
| Single | 5 | 0.9 |
| First marriage | 508 | 97.9 |
| Remarriage | 6 | 1.2 |
| Maternal smoking status during pregnancy | ||
| No | 512 | 98.7 |
| Sometimes | 5 | 0.9 |
| Smoking every day | 2 | 0.4 |
| Paternal smoking status during pregnancy | ||
| No | 298 | 57.4 |
| Sometimes | 49 | 9.4 |
| Smoking every day | 171 | 33.2 |
| Infant gender | ||
| Male | 268 | 51.6 |
| Female | 251 | 48.4 |