TABLE 4.
Absorption estimations from stable iron isotope studies across gestation1
| Stable isotope (57Fe or 54Fe as FeSO4) | ||||||||
|---|---|---|---|---|---|---|---|---|
| Whittaker et al.2,3, (62) (n = 9) | Barrett et al2,3,6 (9) (n = 12) | Whittaker et al2,4 (32) (n = 5) | O’Brien et al4 (42) (n = 43) | Delaney et al4 (10) (n = 5) | Young et al.4,6 (28) (n = 20) | Current study2,4 (n = 15) | Koenig et al.4 (30) (n = 50) | |
| Total iron load, mg | 5.23 | 6 | 10 | 60 | 9 | 9 | 20 | 8.4 |
| Weeks of gestation | Geometric mean [range] | Geometric mean [range] | Geometric mean [range] | Median [range] | Median [range] | Median [range] | Median [range] | Median [IQR] |
| <10 | — | — | — | — | — | — | — | — |
| 10–14 | 7.6 [1.2–21.8] | 7.2 [4.9–10.9] | 11.8 [4.4–24.8] | — | — | — | 8.5 [5.0–27.6] | — |
| 15–19 | — | — | — | — | — | — | — | — |
| 20–24 | 21.1 [8.6–58.4] | 36.3 [27.6–47.3] | — | — | — | — | — | — |
| 25–29 | — | — | — | — | — | — | — | — |
| 30–34 | — | — | — | 13.98 [0.8–33.2] | 37.91 [19.0–62.1] | 40.49 [18.3–62.9] | — | 9.8 [0–20] |
| >35 | 36.3 [18.4–55.6] | 66.1 [57.1–76.2] | 49.0 [38.2–77.2] | 9.32 [1.3–15.6] | — | — | 18.8 [6.2–34.2] | — |
| Fold change weeks 10–14 to >35 | 4.8 | 9.2 | 4.2 | — | — | — | 2.2 | — |
1
Compared with nonpregnant women (DRI 18% absorption).
2
Longitudinal study measures across gestation.
3
Serum iron measured shortly after dosing to calculate absorption.
4
RBC iron incorporation used to calculate absorption.
5 Absorption measures using whole body counter.
6
Iron isotope dose given with food.