Table 1.
Clinical characteristics of participants by passive smoking status
| Variables | Exposure to passive smoking | Nonexposure to passive smoking | p value | All participants |
|---|---|---|---|---|
| N | 8,230 | 6,118 | 14,348 | |
| At the first antenatal care visit, n (%) | ||||
| Age, years | 28.2±2.9 | 28.8±3.0 | <0.0001* | 28.5±2.9 |
| Gestational age, week | 10.4±2.3 | 10.4±2.3 | 0.269* | 10.4±2.3 |
| Height, cm | 163.2±4.7 | 163.2±4.8 | 0.373* | 163.2±4.7 |
| Parity >1 | 296 (3.6) | 248 (4.1) | 0.156** | 544 (3.8) |
| Han ethnicity | 7,833 (95.2) | 5,835 (95.4) | 0.581** | 13,668 (95.3) |
| Education >12 years | 6,578 (85.2) | 5,217 (79.9) | <0.0001** | 11,795 (82.2) |
| DBP, mm Hg | 68.3±7.7 | 68.5±7.8 | 0.120* | 68.4±7.8 |
| SBP, mm Hg | 105.5±10.7 | 105.6±10.8 | 0.576* | 105.5±10.7 |
| Prepregnancy BMI, kg/m2 | 22.5±3.6 | 22.2±3.3 | <0.0001* | 22.4±3.5 |
| Prepregnancy BMI group, kg/m2 | <0.0001** | |||
| <18.5 | 758 (9.2) | 593 (9.7) | 1,351 (9.4) | |
| ≥18.5–<24.0 | 5,149 (62.6) | 3,950 (64.6) | 9,095 (63.4) | |
| ≥24.0–<28.0 | 1,685 (20.5) | 1,214 (19.8) | 2,903 (20.2) | |
| ≥28.0 | 638 (7.8) | 361 (5.9) | 999 (7.0) | |
| At GCT, n (%) | ||||
| GCT, mmol/L | 6.6±1.6 | 6.6±1.5 | 0.661* | 6.6±1.6 |
| GDM | 621 (8.0) | 384 (6.7) | 0.005** | 1,005 (7.0) |
| Alcohol drinker during pregnancy | 597 (7.3) | 248 (4.1) | <0.0001** | 845 (5.9) |
| Weight gin up to GCT, kg | 7.3±3.6 | 7.3±3.9 | 0.342* | 7.3±3.7 |
| At delivery, n (%) | ||||
| Gestational age at delivery, weeks | 39.0±1.5 | 39.1±1.7 | 0.727* | 39.1±1.6 |
| Multiple pregnancies | 0 (0.0) | 145 (1.1) | <0.0001** | 145 (1.0) |
| Preterm birth | 284 (3.5) | 214 (3.5) | 0.879** | 498 (3.5) |
| Infant male gender | 4,285 (52.1) | 3,173 (51.9) | 0.811** | 7,458 (52.0) |
| Infant birth weight | 3,376.1±476.1 | 3,363.0±475.0 | 0.103* | 3,370.5±475.7 |
| LGA | 761 (9.3) | 514 (8.4) | 0.079** | 1,275 (8.9) |
| Macrosomia | 783 (9.5) | 518 (8.5) | 0.031** | 1,301 (9.1) |
| Low birth weight | 238 (2.9) | 184 (3.0) | 0.685** | 422 (2.9) |
| SGA | 396 (4.8) | 323 (5.2) | 0.204** | 719 (5.0) |
| Stillbirth or neonatal death | 12 (0.15) | 3 (0.05) | 0.076** | 15 (0.10) |
BMI, body mass index; GDM, gestational diabetes mellitus; GCT, glucose challenge test; SBP/DBP, systolic/diastolic blood pressure; LGA, large for gestational age; SGA, small for gestational age.
*
Derived from Student's t test.
**
Derived from χ2 test or Fisher's exact test.