Table 1.
Description of the variables studied and comparison with the original population from the 1993 Pelotas (Brazil) Birth Cohort Study
| Characteristic | Original N (%) | Traced in 2008 N (%) |
|---|---|---|
| Sex | 5,248 | 4,018 |
| Male | 2,606 (49.7) | 1,966 (48.9) |
| Female | 2,642 (50.3) | 2,052 (51.1) |
| Skin color | 4,420 | 4,001 |
| White | 2,953 (66.8) | 2,646 (66.1) |
| Black or mixed | 1,259 (28.5) | 1,165 (29.1) |
| Other | 208 (4.7) | 190 (4.8) |
| Maternal smoking during pregnancy | 5,249 | 4,018 |
| No | 3,497 (66.6) | 2,683 (66.8) |
| Yes | 1,752 (33.4) | 1,335 (33.2) |
| Maternal age at delivery (years) | 5,248 | 4,017 |
| <20 | 915 (17.4) | 692 (17.2) |
| 20–34 | 3,756 (71.6) | 2,884 (71.8) |
| ≥35 | 577 (11.0) | 441 (11.0) |
| Gestational age (weeks) | 5,193 | 3,981 |
| ≥37 | 4,582 (88.2) | 3,558 (89.4) |
| <37 | 611 (11.8) | 423 (10.6) |
| Hospitalizations in the first year | 5,249 | 4,018 |
| No | 4,297 (81.9) | 3,323 (82.7) |
| Diarrhea, ARI, or bronchospasm | 430 (8.2) | 324 (8.1) |
| Another reason | 522 (9.9) | 371 (9.2) |
| Parents smoking in 2004 | 3,382 | 3,073 |
| No one | 785 (23.2) | 714 (23.2) |
| At least one former smoker | 932 (27.6) | 862 (28.1) |
| At least one smoker | 1,034 (30.6) | 935 (30.4) |
| Both smoker | 631 (18.6) | 562 (18.3) |
| Family history of asthma, wheezing, or bronchitis | 4,356 | 3,947 |
| No | 2,856 (65.6) | 2,587 (65.5) |
| Yes | 1,500 (34.4) | 1,360 (34.5) |
| Number of people co-sleeping with adolescent | 4,425 | 4,008 |
| Nobody | 1,175 (26.6) | 1,054 (26.3) |
| One to three | 2,868 (64.8) | 2,617 (65.3) |
| Four or more | 382 (8.6) | 337 (8.4) |
| Number of days with GERD symptoms weekly | 4,324 | 4,015 |
| None | 3,631 (84.0) | 3,377 (84.1) |
| One day | 460 (10.6) | 428 (10.7) |
| Two or more days | 233 (5.4) | 210 (5.2) |
| Medical diagnosis of allergy (rhinitis and/or eczema) | 4,214 | 3,976 |
| No | 1,956 (46.4) | 1,831 (46.1) |
| Rhinitis or eczema | 1,812 (43.0) | 1,731 (43.6) |
| Rhinitis and eczema | 446 (10.6) | 413 (10.3) |
| Physical activity trajectory from 11 to 15 years old | 4,092 | 3,880 |
| Inactive in both periods | 1,549 (37.9) | 1,459 (37.6) |
| Active only at 11 years | 871 (21.3) | 830 (21.4) |
| Active only at 15 years | 826 (20.1) | 785 (20.2) |
| Active in both waves | 846 (20.7) | 806 (20.8) |
| Family income from birth to 15 years old | 4,224 | .922 |
| Ever poor | 876 (20.8) | 809 (20.7) |
| Not poor–poor | 540 (12.8) | 503 (12.9) |
| Poor–not poor | 941 (22.2) | 874 (22.3) |
| Never poor | 1,867 (44.2) | 1,726 (44.1) |
| Tanner' pubertal stages (score) | 3,442 | 3,250 |
| 2–4 (least developed) | 191 (5.6) | 176 (5.3) |
| 5–7 | 1,691 (49.1) | 1,597 (49.2) |
| 8–10 (most developed) | 1,560 (45.3) | 1,477 (45.5) |
| Adolescent smoking trajectory at 11 and 15 years old | 4,135 | 3,952 |
| No–no | 3,310 (80.1) | 3,173 (80.3) |
| Yes–no | 53 (1.2) | 49 (1.2) |
| No–yes | 675 (16.3) | 635 (16.1) |
| Yes–yes | 97 (2.4) | 95 (2.4) |
ARI = acute respiratory infection; GERD = gastroesophageal reflux disease.