TABLE 1.
Background characteristics of the sample of Chilean 12-mo-old infants1
| Characteristic | Value2 |
|---|---|
| Infant | |
| Male [n (%)] | 872 (52.6) |
| Gestational age (wk) | 39.4 ± 1.0 (37.0–42.0) |
| Birth weight (kg) | 3.54 ± 0.4 (3.00–5.04) |
| Length at birth (cm) | 50.7 ± 1.7 (42.0–59.0) |
| Weight-for-age at 12 mo (z score) | −0.05 ± 0.9 (32.98–3.53) |
| Length-for-age at 12 mo (z score) | −0.06 ± 0.8 (32.59–3.21) |
| Age at first bottle (mo) | 3.5 ± 3.0 (0–12.5) |
| Nursing at 1 y [n (%)]3 | 555 (34.7) |
| Hemoglobin at 6 mo (g/L) | 114.0 ± 9.3 (84–147) |
| Family | |
| Maternal age (y) | 26.4 ± 6.0 (14.1–46.4) |
| No. of children for mother | 2.1 ± 1.1 (1–9) |
| Maternal education (y) | 9.4 ± 2.6 (1–17) |
| Father absent [n (%)]4 | 208 (15.2) |
| Socioeconomic status index5 | 27.9 ± 6.5 (14–47) |
| Maternal smoking [n (%)]6,7 | 260 (24.9) |
n = 1657. Sample size was smaller for some family variables because of reduced administration of family measures toward the end of the study due to a lack of funding.
All values are x̄ ± SD; range in parentheses, unless indicated otherwise.
n = 1599.
n = 1369.
Socioeconomic status index consisted of items from the Graffar measure (47), a measure of socioeconomic status that is sensitive to differences at the lower range. Items included were the number of persons in household “eating from one pot,” father’s presence in the household, the highest education level of the head of household, property ownership, type of house construction, characteristics of the kitchen, sewage, running water, the number of garbage collections per week, and total count of 6 household goods (car, refrigerator, washing machine, stereo system, black-and-white television, and color television). Index values indicate that the sample had a uniformly low socioeconomic status.
n = 1044.
Of mothers who smoked, 81% reported smoking only 1–5 cigarettes/d; 14% smoked 5–10 cigarettes/d, and 5% smoked >10 cigarettes/d. No mother reported using illicit drugs; 30 mothers reported consuming alcoholic beverages, with 3 reporting >1 drink/wk. Data on these behaviors during pregnancy were not available.