Table I.
Characteristics of mothers and their children (n = 9723)
| Maternal characteristics | Observed | Imputed |
|---|---|---|
| Age (y) | ||
| <20 | 4.3 (404) | 4.3 (417) |
| 20-24 | 19.8 (1873) | 19.8 (1928) |
| 25-29 | 41.8 (3945) | 41.8 (4066) |
| 30-34 | 26.1 (2466) | 26.1 (2537) |
| ≥35 | 8.0 (756) | 8.0 (776) |
| Missing | 2.9 (279) | — |
| Body mass index (kg/m2) | ||
| <20 | 18.2 (1541) | 18.7 (1815) |
| 20-24 | 61.3 (5183) | 59.5 (5793) |
| 25-29 | 15.2 (1282) | 16.7 (1623) |
| ≥30 | 5.3 (448) | 5.1 (492) |
| Missing | 13.1 (1,269) | — |
| Education (%) | ||
| Low/medium | 60.3 (5454) | 60.7 (5902) |
| Higher | 39.7 (3596) | 39.3 (3821) |
| Missing | 6.9 (673) | — |
| History of asthma (%) | ||
| No | 88.8 (8042) | 88.7 (8629) |
| Yes | 11.2 (1018) | 11.3 (1094) |
| Missing | 6.8 (663) | — |
| Anxiety during pregnancy (%) | ||
| No | 73.3 (6162) | 73.3 (7126) |
| Yes | 26.7 (2241) | 26.7 (2597) |
| Missing | 13.6 (1220) | — |
| Smoking during pregnancy (%) | ||
| No | 84.0 (7753) | 83.9 (8159) |
| Yes | 16.0 (1472) | 16.1 (1564) |
| Missing | 5.1 (498) | — |
| Parity (%) | ||
| 0 | 46.0 (4181) | 46.1 (4486) |
| ≥1 | 54.0 (4909) | 53.9 (5237) |
| Missing | 6.5 (633) | — |
| Child characteristics | ||
| Female sex (%) | 49.5 (4814) | 49.5 (4814) |
| Gestational age at birth (wk) | 40.0 (35.0-42.0) | 40.0 (35.0-42.0) |
| Birth weight (g) | 3438 (532) | 3436 (524) |
| Breast-feeding duration (%) | ||
| Never | 23.3 (1999) | 23.7 (2308) |
| <3 mo | 22.9 (1972) | 23.0 (2236) |
| 3-6 mo | 17.1 (1472) | 17.1 (1664) |
| ≥6 mo | 36.8 (3163) | 36.2 (3515) |
| Missing | 11.5 (1117) | — |
Values are means (SDs), medians (2.5th-97.5th percentiles), or percentages (absolute numbers).
Gestational age at birth was missing for 2.9% (n = 279), and birth weight was missing for 3.9% (n = 378).