Table 3.
Univariate Cox proportional hazard model of age at menarche
| Variables | Hazard Ratio (95 % CI) | p-value |
|---|---|---|
| Bodyweight (kg) | 1.013 (1.008–1.017) | <.0001 |
| Height (cm) | 1.003 (0.996–1.010) | .4293 |
| Maternal age at menarche (y) | ||
| Younger (<13.0) | 1.514 (1.256–1.826) | <.0001 |
| Normal (13.0–15.9) | 1.00 | |
| Older (≥16.0) | 0.707 (0.622–0.804) | <.0001 |
| BMI (kg/m2) | ||
| Underweight | 0.327 (0.193–0.554) | <.0001 |
| Normal | 1.00 | |
| Overweight | 1.227 (1.076–1.400) | .0023 |
| Obese | 1.258 (1.058–1.495) | .0093 |
| Household income | ||
| Low | 1.00 | |
| Lower middle | 1.117 (0.978–1.276) | .1030 |
| Upper middle | 1.159 (1.018–1.320) | .0259 |
| High | 1.207 (1.059–1.378) | .0047 |
| Paternal education level | ||
| No schooling | 1.00 | |
| Elementary school | 1.188 (0.571–2.474) | .6446 |
| Middle school | 0.997 (0.487–2.040) | .9924 |
| High school | 1.266 (0.628–2.552) | .5093 |
| College or university | 1.463 (0.752–2.950) | .2880 |
| Maternal education level | ||
| No schooling | 1.00 | |
| Elementary school | 0.974 (0.504–1.880) | .9363 |
| Middle school | 0.895 (0.471–1.701) | .7351 |
| High school | 1.096 (0.585–2.053) | .7740 |
| College or university | 1.370 (0.729–2.577) | .3280 |
| Place of residence | ||
| Rural | 1.00 | |
| Urban | 1.039 (0.954–1.131) | .3804 |