TABLE 5.
Dose-response results in iron-supplemented infants whose mothers received iron in pregnancy: Relations between the number of bottles of iron received and infant iron status at 9 mo1
| Number of bottles of iron |
||||||
| ≤10 (VL) | 11–20 (L) | >20 (M) | P value2 | Significant contrasts3 | RR (95% CI)4 | |
| n | 229 | 66 | 21 | |||
| Iron measures | ||||||
| Hb, g/L | 112 (110, 113) | 114 (111, 117) | 120 (114, 125) | <0.01 | M > VL, L5 | |
| MCV, fL | 68.5 (67.9, 69.0) | 69.3 (68.3, 70.2) | 70.1 (68.3, 71.8) | 0.03 | M5 > VL | |
| SF,6 μg/L | 10.7 (9.6, 12.0) | 13.9 (11.2, 17.1) | 18.3 (12.6, 26.6) | <0.01 | M, L > VL | |
| ZPP/H,6,7 μmol/mol heme | 74.3 (69.3, 79.6) | 70.7 (62.2, 80.3) | 68.3 (54.8, 85.1) | 0.36 | ||
| sTfR,6 nmol/L | 25.3 (24.3, 26.3) | 24.1 (22.4, 26.0) | 19.5 (17.1, 22.3) | <0.001 | M < VL, L | |
| BI | −0.42 (−0.91, 0.07) | 0.67 (−0.24, 1.58) | 2.43 (0.81, 4.04) | <0.001 | M, L > VL | |
| M > L5 | ||||||
| Iron status indicators | ||||||
| ID (cutoff)7 | 142/229 (62.0) | 38/66 (57.6) | 8/21 (38.1) | 0.05 | M vs. VL | 0.61 (0.35, 1.07) |
| ID (BI) | 115/229 (50.2) | 26/66 (39.4) | 5/16 (23.8) | 0.01 | M vs. VL | 0.47 (0.22, 1.03) |
| IDA (cutoff) | 87/229 (38.0) | 16/66 (24.2) | 2/21 (9.5) | <0.01 | L vs. VL | 0.64 (0.40, 1.01) |
| M vs. VL | 0.25 (0.07, 0.95) | |||||
| IDA (BI) | 76/229 (33.2) | 14/66 (21.2) | 1/21 (4.8) | <0.001 | M vs. VL | 0.14 (0.02, 0.98) |
| L5 vs. VL | 0.64 (0.39, 1.05) | |||||
Values are means (95% CIs) for continuous variables and n (%) for categorical ones. BI, body iron; Hb, hemoglobin; ID, iron deficiency; IDA, iron deficiency anemia; L, low; M, medium; MCV, mean corpuscular volume; SF, serum ferritin; sTfR, serum transferrin receptor; VL, very low; ZPP/H, zinc protoporphyrin/heme.
P values are for the linear trend.
Significant contrasts (P < 0.05) are based on general linear models for continuous measures and logistic regression for iron status indicators.
RR is shown for the significant corresponding contrasts for iron status indicators.
Suggestive trend (P < 0.10) is shown to indicate the pattern of findings.
Values are geometric means (95% CIs). Statistical analyses were conducted on log-transformed SF, ZPP/H, and sTfR.
Iron status at birth was a significant covariate for ZPP/H and ID (cutoff). Adjusted values are shown.