Table 1.
Characteristics of participant mothers in each city (MEAN ± SD or %).
| Characteristic | Changchun (n = 244) | Lanzhou (n = 299) | Chengdu (n = 281) | Tianjin (n = 229) | Guangzhou (n = 342) | Shanghai (n = 363) | P value |
|---|---|---|---|---|---|---|---|
| Maternal | |||||||
| Age at delivery, years | 29.9 ± 3.0 | 29.8 ± 4.3 | 29.5 ± 3.3 | 30.3 ± 3.2 | 29.7 ± 3.7 | 30.1 ± 3.0 | 0.054 |
| Pre-pregnancy BMI, kg/m2 | 21.3 ± 3.0 a,b | 21.3 ± 2.8 a,b | 20.7 ± 2.5 b | 21.8 ± 3.4 a | 20.3 ± 2.5 b | 21.2 ± 2.8 a,b | <0.001 |
| Pre-delivery BMI, kg/m2 | 27.4 ± 3.8 a | 26.8 ± 3.0 a,b | 26.2 ± 2.8 b | 27.3 ± 3.4 a | 25.5 ± 3.1 b | 26.7 ± 3.6 a,b | <0.001 |
| Gestational weight gain, Kg | 16.5 ± 5.5 a | 14.3 ± 5.3 b | 14.2 ± 4.6 b | 14.6 ± 7.6 b | 13.5 ± 4.9 b | 14.7 ± 5.5 b | <0.001 |
| Gestational age, weeks | 39.0 ± 1.1 b | 39.0 ± 2.1 a,b | 39.5 ± 1.6 a | 39.2 ± 1.7 a,b | 38.9 ± 1.4 b | 39.6 ± 1.0 a | <0.001 |
| Vaginal delivery, % | 42% a | 59% b | 43% a | 68% b,c | 77% c | 61% b | <0.001 |
| Primipara, % | 95% a | 50% b | 73% c,d | 77% d | 64% c | 74% c,d | <0.001 |
| Infant | |||||||
| Birthweight, g | 3,380.1 ± 401.1 a,b | 3,277.8 ± 445.1 b | 3,409.5 ± 624.7 a,b | 3,396.7 ± 490.8 a | 3,542.6 ± 1,004.9 a,b | 3,332.3 ± 368.2 a,b | 0.025 |
| Birth-length, cm | 50.5 ± 1.7 a | 49.0 ± 2.5 c | 49.8 ± 1.5 b,c | 50.4 ± 2.6 a,b | 50.3 ± 2.3 b | 49.4 ± 1.3 c | <0.001 |
| Female infant, % | 49% | 47% | 43% | 51% | 48% | 53% | 0.159 |
a–dValues within a row in individual cities with different superscript letters were significantly different (adjusted p < 0.05).