Table 1.
Distribution of Background Characteristics Among Children Included in an Analysis of Maternal and Paternal Stress and Childhood Asthma, Norwegian Mother and Child Cohort Study, 2000–2007
| Background Characteristic | Maternal Psychosocial Stress (n = 63,626) | Paternal Psychosocial Stress (n = 47,619) | ||
|---|---|---|---|---|
| No. of Children | % | No. of Children | % | |
| Maternal age at delivery, yearsa | 30.1 (4.5) | 30.1 (4.4) | ||
| Maternal parity | ||||
| 0 | 28,413 | 44.7 | 22,374 | 47.0 |
| 1 | 22,650 | 35.6 | 16,617 | 34.9 |
| 2 | 9,849 | 15.5 | 6,860 | 14.4 |
| ≥3 | 2,714 | 4.3 | 1,768 | 3.7 |
| Maternal education | ||||
| Less than high school | 4,795 | 7.5 | 3,274 | 6.9 |
| High school | 19,318 | 30.4 | 13,851 | 29.1 |
| ≤4 years of college | 26,261 | 41.3 | 20,021 | 42.0 |
| >4 years of college | 12,996 | 20.4 | 10,267 | 21.6 |
| Missing data | 256 | 0.4 | 206 | 0.4 |
| Maternal prepregnancy body mass indexb | ||||
| <18.5 | 1,817 | 2.9 | 1,340 | 2.8 |
| 18.5–24.9 | 40,453 | 63.6 | 30,259 | 63.5 |
| 25–29.9 | 13,854 | 21.8 | 10,397 | 21.8 |
| ≥30 | 5,858 | 9.2 | 4,435 | 9.3 |
| Missing data | 1,644 | 2.6 | 1,188 | 2.5 |
| Maternal smoking during pregnancy | ||||
| None | 48,184 | 75.7 | 36,654 | 77.0 |
| Quit by 18 weeks | 8,991 | 14.1 | 6,661 | 14.0 |
| Smoked after 18 weeks | 6,182 | 9.7 | 4,112 | 8.6 |
| Missing data | 269 | 0.4 | 192 | 0.4 |
| Maternal smoking during first 6 months of child’s life | ||||
| No | 52,124 | 81.9 | 39,517 | 83.0 |
| Yes | 8,879 | 14.0 | 6,174 | 13.0 |
| Missing data | 2,623 | 4.1 | 1,928 | 4.1 |
| Maternal history of asthma | ||||
| No | 58,924 | 92.6 | 44,027 | 92.5 |
| Yes | 4,702 | 7.4 | 3,592 | 7.5 |
| Paternal age, years | ||||
| <25 | 2,851 | 4.5 | 2,083 | 4.4 |
| 25–29 | 14,592 | 22.9 | 11,040 | 23.2 |
| 30–34 | 25,101 | 39.5 | 19,235 | 40.4 |
| ≥35 | 20,955 | 32.9 | 15,259 | 32.0 |
| Missing data | 127 | 0.2 | 2 | 0 |
| Paternal education | ||||
| Less than high school | 6,772 | 10.6 | 4,441 | 9.3 |
| High school | 25,631 | 40.3 | 18,691 | 39.3 |
| ≤4 years of college | 16,679 | 26.2 | 13,082 | 27.5 |
| >4 years of college | 12,638 | 19.9 | 10,089 | 21.2 |
| Missing data | 1,906 | 3.0 | 1,316 | 2.8 |
| Paternal body mass index | ||||
| <18.5 | 128 | 0.2 | 99 | 0.2 |
| 18.5–24.9 | 27,149 | 42.7 | 20,122 | 42.3 |
| 25–29.9 | 27,565 | 43.3 | 20,846 | 43.8 |
| ≥30 | 5,829 | 9.2 | 4,560 | 9.6 |
| Missing data | 2,955 | 4.6 | 1,992 | 4.2 |
| Paternal smoking | ||||
| No | 45,830 | 72.0 | 35,388 | 74.3 |
| Yes | 17,490 | 27.5 | 12,050 | 25.3 |
| Missing data | 306 | 0.5 | 181 | 0.4 |
| Paternal history of asthma | ||||
| No | 43,462 | 68.3 | 43,462 | 91.3 |
| Yes | 4,157 | 6.5 | 4,157 | 8.7 |
| Missing data | 16,007 | 25.2 | 0 | 0 |
| Child’s sex | ||||
| Male | 32,562 | 51.2 | 24,329 | 51.1 |
| Female | 31,064 | 48.8 | 23,290 | 48.9 |
| Child’s birth weight, ga | 3,621 (545) | 3,613 (543) | ||
| Missing data | 31 | 0.1 | 22 | 0.1 |
| Child’s gestational age, weeksa | 39.5 (1.7) | 39.5 (1.7) | ||
| Missing data | 244 | 0.4 | 188 | 0.4 |
| Child still breastfeeding at age 6 months | ||||
| No | 11,554 | 18.2 | 8,574 | 18.0 |
| Yes | 52,072 | 81.8 | 39,045 | 82.0 |
a Values are expressed as mean (standard deviation).
b Weight (kg)/height (m)2.