Table 2.
Associations between iron stores and enrollment confounders, and hemoglobin levels and anemia over the entire study period
| Variable | Hemoglobin levels (g/L) |
Anemiaa |
|||
|---|---|---|---|---|---|
| Unadjusted mean difference (95% CI); p value | Adjusted mean difference (95% CI); p value | Unadjusted odds ratio (95% CI); p value | Adjusted odds ratio (95% CI); p value | ||
| Iron stores | |||||
| Ferritin (log2(μg/l))b | – | 1.99 (1.41, 2.58); <0.001 | – | 0.65 (0.57, 0.73); <0.001 | – |
| Iron deficiencyc |
replete | Ref. | Ref. | Ref. | Ref. |
| deficient |
−8.29 (−10.20, −6.38); <0.001 |
−8.07 (−10.12, −6.01); <0.001 |
4.26 (2.70, 6.71); <0.001 |
4.60 (2.79, 7.58); <0.001 |
|
| At enrollment | |||||
| Age (years) | – | −0.001 (−0.17, 0.16); 0.99 | 0.03 (−0.18, 0.23); 0.79 | 1.00 (0.97, 1.03); 0.93 | 1.01 (0.96, 1.05); 0.74 |
| Gravidity | primigravida | Ref. | Ref. | Ref. | Ref. |
| multigravida | −2.65 (−4.76, −0.54); 0.·01 | −2.63 (−5.26, −0.01); 0.05 | 1.34 (0.94, 1.92); 0.11 | 1.18 (0.67, 2.08); 0.56 | |
| Smoking status | never | Ref. | Ref. | Ref. | Ref. |
| current/past | −0.91 (−2.78, 0.95); 0.34 | −1.24 (−3.28, 0.80); 0.23 | 1.23 (0.89, 1.69); 0.21 | 1.45 (0.93, 2.27); 0.11 | |
| MUAC (cm) | 0.63 (0.32, 0.93); <0.001 | 0.51 (0.13, 0.90); 0.01 | 0.90 (0.86, 0.95); <0.001 | 0.89 (0.82, 0.96); 0.01 | |
| >23 cm | Ref. | – | Ref. | – | |
| ≤23 cm | −3.59 (−6.23, −0.95); 0.01 | – | 1.61 (1.00, 2.61); 0.05 | – | |
| Feverd | no | Ref. | Ref. | Ref. | Ref. |
| yes | −0.95 (−3.68, 1.77); 0.49 | −0.10 (−2.97, 2.78); 0.95 | 1.03 (0.64, 1.64); 0.91 | 0.84 (0.46, 1.56); 0.59 | |
| Plasmodium spp. (PCR) | negative | Ref. | Ref. | Ref. | Ref. |
| positive | −6.48 (−9.41, −3.55); <0.001 | −4.12 (−7.30, −0.93); 0.01 | 2.55 (1.44, 4.49); <0.001 | 1.99 (0.92, 4.26); 0.08 | |
| α+-Thalassemia | wild type | Ref. | Ref. | Ref. | Ref. |
| Het/Hom | −5.74 (−8.17, −3.32); <0.001 | −5.78 (−8.48, −3.08); <0.001 | 2.86 (1.78, 4.62); <0.001 | 3.15 (1.58, 6.28); 0.001 | |
| CR1 deficiency | H/H | Ref. | Ref. | Ref. | Ref. |
| H/L | 2.20 (−1.71, 6.12); 0.27 | 2.96 (−1.19, 7.11); 0.16 | 0.99 (0.51, 1.93); 0.97 | 0.68 (0.26, 1.75); 0.42 | |
| L/L | 2.08 (−1.73, 5.89); 0.29 | 2.72 (−1.34, 6.79); 0.19 | 1.01 (0.53, 1.95); 0.97 | 0.69 (0.27, 1.75); 0.43 | |
| SAO | normal | Ref. | Ref. | Ref. | Ref. |
| SAO | −3.22 (−7.34, 0.91); 0.13 | −2.50 (−6.64, 1.64); 0.24 | 1.16 (0.56, 2.39); 0.70 | 0.90 (0.37, 2.17); 0.81 | |
Estimated mean hemoglobin differences and odds ratios for anemia were derived from linear and logistic mixed-effects models, respectively, with a random effect for the individual-specific intercept. Adjusted models included enrollment variables listed in the table and time (enrollment, birth, and 6 and 12 months postpartum). CI, confidence interval; Het, heterozygous; Hom, homozygous; CR1, complement receptor 1; H/H, high CR1 expression; H/L, intermediate CR1 expression; L/L, low CR1 expression; SAO, Southeast Asian ovalocytosis.
Anemia defined as hemoglobin <110 g/L in pregnancy and hemoglobin <120 g/L in the postpartum period.
Ferritin transformed to log base-2 due to positively skewed distribution, thus the coefficient/odds ratio represents the change associated with a 2-fold increase in ferritin.
Iron deficient: ferritin <15 μg/L in pregnancy and postpartum; iron replete: ferritin ≥15 μg/L and CRP ≤10 mg/L in pregnancy and ferritin ≥15 μg/L and CRP ≤5 mg/L postpartum.
Self-reported history of fever during the pregnancy prior to their first antenatal care appointment.