TABLE 1.
Demographic characteristics and biomarkers of mothers (n = 212)1
| Characteristic | Value |
|---|---|
| Age at 5 mo postpartum, y | 28.4 ± 6.4 |
| Wealth index2 | 0.0 ± 1.3 |
| Education | |
| Elementary school (6–7 y old/6-y duration) | 42 (19.8) |
| Junior high school (12–13 y old/3-y duration) | 73 (34.4) |
| Senior high school (15–16 y old/≥3-y duration) | 97 (45.8) |
| Rural location | 104 (49.1) |
| Infant sex female | 104 (49.1) |
| Infant birthweight, g | 3126 ± 344 |
| Primiparous | 70 (33.0) |
| Time since last pregnancy,3 mo | 45 (0, 80) |
| Height at 5 mo postpartum, cm | 151 ± 5 |
| Maternal height <145 cm | 28 (13.2) |
| BMI at 5 mo postpartum | 24.3 ± 3.9 |
| Weight status at 5 mo postpartum4 | |
| Underweight | 9 (4.2) |
| Overweight | 68 (32.1) |
| Obese | 16 (7.6) |
| Human milk volume | |
| 2 mo postpartum (83% EBF) | 746 ± 214 |
| 5 mo postpartum (43% EBF) | 701 ± 187 |
| Biomarkers at 5 mo postpartum5 (n = 163) | |
| Hemoglobin, g/L | 132 ± 12 |
| Hemoglobin <120 g/L | 25 (15.3) |
| Iron serum ferritin, geometric mean (95% CI) μg/L | 24.9 (21.5, 28.8) |
| Iron serum ferritin <15 μg/L | 40 (24.5) |
| Iron sTfR, geometric mean (95% CI) mg/L | 6.27 (5.99, 6.57) |
| Iron sTfR >8.3 mg/L | 26 (16.0) |
| Iron BIS, mg/kg | 4.36 ± 4.20 |
| Iron BIS <0 mg/kg | 25 (15.3) |
| IDA (hemoglobin <120 g/L and BIS <0 mg/kg) | 12 (7.4) |
| Zinc, μmol/L | 10.4 ± 1.3 |
| Zinc <10.7 μmol/L | 98 (60.1) |
| RBP, geometric mean (95% CI) μmol/L | 1.33 (1.28, 1.39) |
| RBP <1.20 μmol/L | 56 (34.4) |
| Selenium, μmol/L | 1.10 ± 0.16 |
| Selenium <0.82 μmol/L | 4 (2.5) |
| Selenium <0.89 μmol/L | 12 (7.4) |
| Selenium <1.0 μmol/L | 35 (21.5) |
| Selenium <1.1 μmol/L | 85 (52.2) |
| Vitamin B-12, pmol/L | 301 ± 117 |
| Vitamin B-12 <148 pmol/L | 0 |
| CRP, median (25th, 75th percentiles) mg/L | 1.14 (0.45, 2.54) |
| CRP >5 mg/L | 24 (14.7) |
| AGP, median (25th, 75th percentiles) g/L | 0.83 (0.63, 1.07) |
| AGP >1 g/L | 53 (32.5) |
Values are means ± SDs, number of participants (%), or median (25th, 75th percentile) unless otherwise indicated. AGP, α-1-acid-glycoprotein; BIS, body iron stores; CRP, C-reactive protein; EBF, exclusively breastfed; IDA, iron deficiency anemia; RBP, retinol binding protein; sTfR, serum transferrin receptor.
An asset-based wealth index derived following the Demographic Health Survey Wealth Index guidelines (33), from principal component analysis.
Pregnancy distance between the previous child and the infant participant in the study, when child was born.
Underweight defined as BMI <18.5; overweight as BMI ≥25 and <30; obese defined as BMI ≥30.
Cutoffs used to define deficiency for each biomarker were as follows: hemoglobin, <120 g/L; adjusted ferritin, <15 μg/L (20, 21); adjusted BIS, <0 mg/kg (19); adjusted sTfR, >8.3 mg/L (16); adjusted zinc, <10.7 μmol/L (22); adjusted RBP, <1.20 μmol/L (23); adjusted selenium, <0.82 μmol/L (16), <0.89, <1.0, <1.1 μmol/L (34); vitamin B-12, <148 pmol/L (24). Zinc adjusted for time of the day and interval since the last meal = exp (unadjusted in biomarkers) + regression coefficient for time of day × [(time of day − regression coefficient for interval since previous meal) × interval since previous meal]. Ferritin, sTfR, RBP, zinc, and selenium adjusted for inflammation = exp (unadjusted in biomarkers − regression coefficient for CRP) × (CRP − maximum of lowest decile for CRP) – [regression coefficient for AGP × (AGP − maximum of lowest decile for AGP)].