Table 1.
Characteristics of the study population
| Maternal smoking: timing | Paternal smoking: any smoking1 | |||||||
|---|---|---|---|---|---|---|---|---|
| Total mothers (N = 1261) | Never smoking mother (N = 708) | Former smoking mother (N = 251) | Early quitting mother (N = 125) | Sustained smoking mother (N = 177) | Total fathers (N = 938) | Nonsmoking father (N = 656) | Smoking father (N = 282) | |
| Maternal age (y) | 31.7 (4.2) | 32.0 (3.9) | 31.9 (3.9) | 31.5 (4.2) | 30.3 (5.5) | 31.9 (3.9) | 32.1 (3.8) | 31.5 (4.0) |
| Maternal BMI (kg/m2) | 23.2 (3.8) | 23.3 (3.9) | 23.5 (3.9) | 22.5 (2.9) | 23.2 (4.1) | 23.4 (3.9) | 23.2 (3.8) | 23.7 (4.1) |
| Maternal education2 | ||||||||
| Low | 441 (35.0) | 205 (29.0) | 84 (33.5) | 40 (32.0) | 112 (63.3) | 282 (30.1) | 186 (28.4) | 96 (34.0) |
| High | 820 (65.0) | 503 (71.0) | 167 (66.5) | 85 (68.0) | 65 (36.7) | 656 (69.9) | 470 (72.6) | 186 (66.0) |
| Parity | ||||||||
| Nulliparous | 764 (60.6) | 414 (58.5) | 166 (66.1) | 88 (70.4) | 96 (54.2) | 570 (60.8) | 382 (58.2) | 188 (66.7) |
| Multiparous | 497 (39.4) | 294 (41.5) | 85 (33.9) | 37 (29.6) | 81 (45.8) | 368 (39.2) | 274 (41.8) | 94 (33.3) |
| Newborn sex | ||||||||
| Male | 640 (50.8) | 345 (48.7) | 130 (51.8) | 61 (48.8) | 104 (58.8) | 467 (49.8) | 317 (48.3) | 150 (53.2) |
| Female | 621 (49.2) | 363 (51.3) | 121 (48.2) | 64 (51.2) | 73 (41.2) | 471 (50.2) | 339 (51.7) | 132 (46.8) |
| Birth weight SDS3 | 0.10 (0.99) | 0.16 (0.95) | 0.17 (0.97) | 0.18 (0.97) | −0.33(1.06) | 0.17 (0.96) | 0.20 (0.95) | 0.09 (0.95) |
| Paternal age (y) | 34.2 (4.9) | 34.4 (4.9) | 33.6 (4.8) | |||||
| Paternal BMI (kg/m2) | 25.2 (3.1) | 25.1 (3.1) | 25.2 (3.1) | |||||
Table displays characteristics of participants included in the main models of the maternal smoking timing analysis and the paternal smoking analysis. For characteristics of participants included in the dose analysis, see Supplementary Table 1. Values are mean (standard deviation) or N (percentage). (1) Analysis of paternal smoking among newborns with never or former smoking mothers only. For results of the sensitivity analysis among all newborns, see Supplementary Table 3e. (2) Highest completed education, categorized into lower (secondary education or less) versus higher (more than secondary education). (3) Birthweight corrected for sex and gestational age at birth.14 Missing data: maternal smoking timing (N = 135), paternal smoking (N = 458), maternal BMI (N = 205), maternal education (N = 20), parity (N = 2), birthweight (N = 1), paternal age (N = 18), and paternal BMI (N = 51). BMI = body mass index; SDS = standard deviation score.