Table 3.
Biomarker iodine and selenium concentrations in gestational week 29 (GW29), gestational week 34 (GW34), and at 4 months postpartum (4M) for all included mothers and infants and grouped by use of multivitamin supplement with minerals.
| Biomarker | n | All Median (5–95th) | n | Supplement Median (5−95th) | n | No supplement Median (5−95th) | p |
|---|---|---|---|---|---|---|---|
| IODINE | |||||||
| Maternal urine, μg/L (GW29)1 | 588 | 113 (53.5–313) | 224 | 152 (61.6–346) | 338 | 98.6 (49.3–204) | <0.001 |
| Breast milk, μg/kg (4M) | 332 | 76.6 (32.6–204) | 63 | 100 (39.1–213) | 263 | 74.2 (31.9–200) | 0.007 |
| Infant urine, μg/L (4M)2 | 369 | 114 (47.9–243) | 60 | 137 (48.0–335) | 293 | 110 (47.8–220) | 0.002 |
| Breastfed3 | 222 | 110 (46.1–248) | 38 | 144 (42.0–352) | 179 | 106 (45.9–219) | <0.001 |
| Not breastfed3 | 147 | 117 (58.2–237) | 22 | 114 (68.5–421) | 114 | 115 (57.7–228) | 0.727 |
| SELENIUM | |||||||
| Maternal plasma, μg/kg (GW29) | 590 | 64.7 (44.9–91.0) | 227 | 69.6 (49.5–96.0) | 335 | 61.9 (42.6–89.4) | <0.001 |
| Maternal erythrocytes, μg/kg (GW29) | 591 | 106 (78.3–146) | 227 | 109 (80.8–148) | 335 | 104 (76.3–145) | 0.002 |
| Breast milk, μg/kg (4M) | 332 | 9.00 (5.73–13.5) | 63 | 9.36 (6.07–13.7) | 263 | 8.92 (5.70–13.3) | 0.017 |
| Infant erythrocytes, μg/kg (4M) | 229 | 96.5 (74.0–134) | 43 | 94.0 (71.2–153) | 178 | 97.3 (73.4–132) | 0.915 |
| Breastfed3 | 138 | 95.7 (73.2–134) | 33 | 94.0 (73.3–147) | 104 | 96.4 (71.1–134) | 0.960 |
| Not breastfed3 | 91 | 97.0 (77.0–134) | 10 | 94.7 (84.3–134)4 | 74 | 97.8 (77.4–129) | 0.740 |
Differences between supplement group and non-supplement group were tested with Mann-Whitney U test. Supplement use was defined as regular consumption (every day or several days a week) of multivitamins with minerals. One individual can be present in supplement group during pregnancy, but in non-supplement group during lactation.
Adjusted to the mothers mean urinary specific gravity (SGmean = 1.017).
Adjusted to the infants mean urinary specific gravity (SGmean = 1.004).
Individuals with available breast milk samples at 4 months were defined as being breastfed.
25−75th Percentile.