TABLE 2.
Iron status indicators in umbilical cord blood from newborns born to women carrying multiple fetuses and teens carrying singletons1
| Variable | n | Whole population | n | Multiples cohort | n | Teen cohort |
|---|---|---|---|---|---|---|
| Hb, g/dL | 224 | 14.8 ± 2.5 | 112 | 15.4 ± 2.18 | 112 | 14.2 ± 2.7 |
| Anemia | 40 | 18 | 11 | 108 | 29 | 26 |
| SF, μg/L | 288 | 111 (102, 121) | 126 | 104 (90.4, 119) | 162 | 117 (105, 132) |
| Erythrocyte iron,2 mg/kg | 224 | 40.9 ± 6.9 | 112 | 42.6 ± 5.68 | 112 | 39.2 ± 7.6 |
| Storage iron,3 mg/kg | 288 | 15.9 ± 7.5 | 126 | 15.3 ± 7.6 | 162 | 16.5 ± 7.3 |
| sTfR, mg/L | 288 | 6.8 (6.4, 7.1) | 126 | 6.0 (5.6, 6.4)8 | 162 | 7.5 (7.1, 8.0) |
| sTfR index4 | 288 | 3.4 (3.2, 3.5) | 126 | 3.0 (2.7, 3.3)8 | 162 | 3.7 (3.4, 3.9) |
| TBI,5 mg/kg | 223 | 53.6 ± 7.2 | 112 | 56.1 ± 6.28 | 111 | 51.0 ± 7.3 |
| Serum Fe, mg/L | 253 | 2.5 (2.3, 2.7) | 124 | 2.8 (2.6, 3.1)8 | 129 | 2.2 (2.0, 2.4) |
| IL-6,6 pg/mL | — | — | 123 | 3.6 (3.1, 4.2) | 145 | 9.0 (7.0, 11.6) |
| CRP,6 mg/L | — | — | 122 | 0.10 (0.09, 0.11) | 94 | 0.28 (0.23, 0.35) |
| Undetectable7 | — | — | 39 | 32 | 19 | 20 |
| Folate, nmol/L | 201 | 46.6 (43.7, 49.7) | 117 | 36.4 (34.3, 38.7) | 84 | 65.4 (59.9, 71.5) |
| <6.8 nmol/L | 0 | 0 | 0 | 0 | 0 | 0 |
| Vitamin B-12, pmol/L | 179 | 536 (495, 583) | 108 | 517 (464, 575) | 71 | 570 (501, 647) |
| <148 pmol/L | 1 | 1 | 0 | 0 | 1 | 1 |
Values are means ± SDs, geometric means (95% CIs) for transformed variables, or percentages. CRP, C-reactive protein; Fe, iron; Hb, hemoglobin; IL-6, interleukin-6; SF, serum ferritin; sTfR, soluble transferrin receptor; TBI, total body iron.
Erythrocyte iron (mg/kg) was calculated as neonatal hemoglobin (g/L) × estimated blood volume (L/kg) × birth weight (kg) × 3.4 (mg/g).
Storage iron (mg/kg) was calculated using the logarithmic relation between SF and body storage iron (62).
sTfR index was calculated as the following: sTfR/log10(SF).
TBI was calculated with the following equation: TBI (mg/kg) = −[log(sTfR/SF) − 2.8229] / 0.1207.
IL-6 and CRP were not assessed between cohorts because they were measured with different assays.
Undetectable was classified as below the limit of detection for CRP of this kit. In the teen cohort this was 0.2 mg/L and in the multiples cohort this was 0.077 mg/L.
Significant difference between cohorts, P < 0.05.