Table 1.
Distribution of study subjects by demographic and risk factors.
| Characteristics a | Total (N = 486) | Included (N = 363) | Excluded (N = 123) |
|---|---|---|---|
| Maternal age at delivery (years) * | 30.8 (4.7) | 30.4 (4.7) | 32.1 (4.3) |
| Maternal BMI (kg/m2) | 20.9 (3.1) | 21 (3.3) | 20.6 (2.4) |
| Parental education level b | |||
| Not senior high school graduated (%) | 3 (0.6) | 3 (0.8) | 0 (0) |
| Senior high school graduated (%) | 24 (4.3) | 19 (5.3) | 2 (1.6) |
| Four–year college /university and above (%) | 485 (95.1) | 340 (93.9) | 121 (98.4) |
| Delivery method, vaginal (%) | 60.1 | 60.5 | 58.9 |
| Infants | |||
| Boys (%) | 50.6 | 49.5 | 54 |
| Birth weight (g) | 3157.9 (476.6) | 3141.7 (490.0) | 3204.7 (433.9) |
| Gestational age (weeks) * | 38.5 (1.7) | 38.4 (1.8) | 38.8 (1.5) |
| Low birth weight (<2500 g) (%) | 28 (5.8) | 25 (6.9) | 3 (2.4) |
| Small gestational age (%) | 32 (6.6) | 23 (6.4) | 9 (7.3) |
| Preterm birth (<37 weeks) (%) * | 42 (8.6) | 39 (10.7) | 3 (2.4) |
| Cord blood | |||
| Cotinine (ng/mL) * | 3.4 (19.2) | 4.5 (22.3) | 0.8 (5.8) |
| LINE-1 methylation (%) | 80.2 (3.99) | ||
| Alu methylation (%) | 20.7 (1.72) |
a All characteristics are expressed as mean (SD) or percentage. b Highest education level of either parent. * p < 0.05 by comparing included and excluded participants.