Table 1. Sociodemographic characteristics of the subjects who used formula only and those who breastfed with or without formula.
| Variables | Formula only n = 125 |
Breastfeeding n = 572 |
Total n = 697 |
P value* |
|---|---|---|---|---|
| Maternal age at birth, yr mean ± SD | 30.0 ± 3.5 | 30.1 ± 3.5 | 30.1 ± 3.5 | 0.766 |
| Maternal education, No. (%) | ||||
| High school or lower | 54 (43.2) | 144 (25.2) | 198 | 0.001 |
| College degree | 15 (12.0) | 87 (15.2) | 102 | |
| University or higher | 54 (43.2) | 332 (58.0) | 386 | |
| Unknown | 2 (1.6) | 9 (1.6) | 11 | |
| Family income, No. (%) | ||||
| < 2,000 USD | 37 (29.6) | 148 (25.9) | 185 | 0.041 |
| 2,000-3,999 USD | 75 (60.0) | 301 (52.6) | 376 | |
| ≥ 4,000 USD | 10 (8.0) | 103 (18.0) | 113 | |
| Unknown | 3 (2.4) | 20 (3.5) | 23 | |
| Maternal employment status, No. (%) | ||||
| Unemployed | 83 (66.4) | 348 (60.8) | 431 | 0.485 |
| Employed | 33 (26.4) | 181 (31.7) | 214 | |
| Unknown | 9 (7.2) | 43 (7.5) | 52 | |
| Sex of infant, No. (%) | ||||
| Boy | 73 (58.4) | 295 (51.6) | 368 | 0.166 |
| Girl | 52 (41.6) | 277 (48.4) | 329 | |
| Gestational age | (n = 122) | (n = 558) | (n = 680) | 0.098 |
| Mean weeks ± SD | 38.6 ± 1.49 | 38.9 ± 1.50 | 38.8 ± 1.50 | |
| Birth weight (g) | (n = 118) | (n = 497) | (n = 615) | 0.871 |
| Mean ± SD | 3426 ± 243 | 3422 ± 278 | 3422 ± 272 | |
| MDI scores (Mean ± SD) | ||||
| 12 mon of age | 97.8 ± 16.66 | 101.8 ± 15.23 | 101.1 ± 15.56 | 0.009 |
| 24 mon of age | 93.1 ± 14.49 | 97.5 ± 14.53 | 96.7 ± 14.61 | 0.005 |
| 36 mon of age | 87.5 ± 13.44 | 93.2 ± 14.35 | 92.1 ± 14.34 | 0.001 |
| PDI scores (Mean ± SD) | ||||
| 12 mon of age | 91.5 ± 16.68 | 94.4 ± 15.74 | 93.9 ± 15.94 | 0.062 |
| 24 mon of age | 97.2 ± 12.98 | 95.9 ± 14.01 | 96.1 ± 13.82 | 0.385 |
| 36 mon of age | 88.8 ± 12.80 | 90.9 ± 13.34 | 90.5 ± 13.25 | 0.198 |
*P value estimated by chi-square or t-test. MDI, mental development index; PDI, psychomotor development index.