TABLE 1.
Sample characteristics and iron status measures by maternal prepregnancy BMI1
| Maternal prepregnancy BMI, kg/m2 | |||||
|---|---|---|---|---|---|
| Underweight (<18.5) (n = 49) (12.1%) | Normal weight (≥18.5 and <25) (n = 246) (60.7%) | Overweight (≥25 and <30) (n = 94) (23.2%) | Obese (≥30) (n = 16) (4.0%) | F or χ2 value | |
| Maternal characteristics at enrollment (mid-pregnancy) | |||||
| Age, y | 23.7 ± 3.4 | 24.3 ± 3.4 | 25.2 ± 4.2 | 23.9 ± 2.4 | 2.6* |
| Gave birth previously, % | 20.4 | 23.5 | 27.5 | 25.0 | 0.99 |
| Weeks of gestation | 16.2 ± 2.3 | 15.9 ± 1.9 | 16.1 ± 2.2 | 15.2 ± 1.9 | 1.1 |
| BMI, kg/m2 | 17.6 ± 0.76 | 21.2 ± 1.8 | 26.9 ± 1.3 | 31.7 ± 1.5 | 637*** |
| Pregnancy and birth outcomes | |||||
| Weight gain, kg | 18.1 ± 5.3 | 18.1 ± 5.6 | 16.2 ± 6.1 | 18.0 ± 7.3 | 2.4* |
| Excessive weight gain,2 % | 40.8 | 67.9 | 80.9 | 100 | 32.6*** |
| Gestational age at birth, wk | 39.8 ± 1.3 | 39.6 ± 1.1 | 39.6 ± 1.1 | 39.3 ± 1.0 | 0.77 |
| Birth weight, g | 3301 ± 382 | 3346 ± 381 | 3474 ± 369 | 3584 ± 395 | 4.9*** |
| Maternal mid-pregnancy iron and anemia status | |||||
| Hb, g/L | 117.9 ± 10.2 | 121.8 ± 9.6 | 124.7 ± 8.4 | 128.8 ± 7.4 | 8.5*** |
| Anemia (Hb <110 g/L), % | 18.4 | 12.6 | 4.3 | 6.3 | 8.0** |
| SF, μg/L | 42.2 ± 35.4 | 42.3 ± 36.6 | 39.5 ± 26.6 | 46.8 ± 40.8 | 0.28 |
| Iron depletion (SF <15 μg/L), % | 14.3 | 16.3 | 19.2 | 12.5 | 0.85 |
| sTfR, nmol/L | 15.4 ± 5.0 | 15.3 ± 5.0 | 17.0 ± 6.6 | 17.6 ± 8.9 | 2.7** |
| hsCRP, mg/L | 3.6 ± 6.6 | 3.1 ± 3.4 | 6.0 ± 5.7 | 4.8 ± 3.4 | 9.5*** |
| Hepcidin, μg/L | 9.4 ± 7.1 | 10.3 ± 8.3 | 8.9 ± 5.6 | 9.0 ± 4.6 | 0.88 |
| Neonatal iron and anemia status (cord blood) | |||||
| Hb, g/L | 147.2 ± 15.2 | 150.5 ± 15.4 | 151.8 ± 14.5 | 151.4 ± 13.6 | 1.0 |
| Anemia (Hb <130 g/L), % | 12.2 | 8.1 | 5.3 | 0 | 3.6 |
| Ferritin, μg/L | 143.2 ± 79.2 | 121.0 ± 71.0 | 109.1 ± 73.9 | 122.0 ± 66.7 | 2.4* |
| Low ferritin (<75 μg/L), % | 12.2 | 27.2 | 34.0 | 37.5 | 8.6** |
| sTfR, nmol/L | 32.6 ± 10.8 | 33.5 ± 14.1 | 34.7 ± 13.9 | 37.6 ± 26.2 | 0.66 |
| hsCRP, mg/L | 0.04 ± 0.20 | 0.02 ± 0.03 | 0.14 ± 0.97 | 0.01 ± 0.01 | 1.5 |
| Hepcidin, μg/L | 18.2 ± 12.8 | 14.9 ± 8.9 | 12.7 ± 8.0 | 14.0 ± 7.1 | 3.8** |
1
Values are means ± SDs or percentages. Differences in means and proportions were assessed using ANOVA (F values reported) and chi-square tests (χ2 statistic reported), respectively. *,**,***Significant difference: *P < 0.1, **P < 0.05, ***P < 0.01. Hb, hemoglobin; hsCRP, high-sensitivity C-reactive protein; SF, serum ferritin; sTfR, soluble transferrin receptor.
2
Excessive gestational weight gain was defined according to Institute of Medicine recommendations based on the difference in weight prepregnancy and at term (33).