Table 1. Comparison of the baseline characteristics of thefinal cohort and the population lost to follow-up.
| The final cohort | The population lost to follow-up | p valuea | |
|---|---|---|---|
| (n = 772) | (n = 354) | ||
| Age (years) | 26.01 ± 3.18 | 25.93 ± 3.34 | 0.08 |
| Pre-pregnancy BMI (kg/m2) | 19.74 ± 2.45 | 19.72 ± 2.31 | 0.07 |
| Education | <0.001 | ||
| Elementary/none | 2 (0.3) | 2 (0.6) | |
| Junior high school | 85 (11) | 86 (24.5) | |
| High school | 190 (24.6) | 97 (27.5) | |
| Junior college | 230 (29.8) | 94 (26.3) | |
| College | 265 (34.3) | 75 (21.1) | |
| Occupation | <0.001 | ||
| White-collar worker | 253 (32.8) | 101 (28.4) | |
| Blue-collar worker | 275 (35.6) | 106 (30) | |
| Farmer/other | 48 (6.2) | 36 (10.3) | |
| Housewife/retired | 196 (25.4) | 111 (31.3) | |
| Income level (yuan/month) | 0.03 | ||
| <1000 | 7 (0.9) | 7 (2) | |
| 1000- | 83 (10.8) | 57 (16.2) | |
| 3001- | 265 (34.3) | 119 (33.5) | |
| 5001- | 305 (39.5) | 132 (37.3) | |
| 10,001- | 112 (14.5) | 39 (11) | |
| Exercise (yes) | 191 (24.7) | 90 (25.4) | 0.94 |
| Smoking (yes) | 21 (2.7) | 60 (1.7) | 0.28 |
| Alcohol (yes) | 20 (2.6) | 60 (1.7) | 0.28 |
Continuous variables are shown as means ± SDs, and categorical variables are shown as n(percentages). aChi-square test for categorical variables and Student ttest for continuous variables.