Table 1. Baseline characteristics of women before pregnancy in north eastern Tanzania.
| All | Anemic (Hb<12g/dL) | Non-anemic (Hb≥12g/dL) | |||||
| Characteristics | N | % (95% CI) /median (IQR) | n | % (95% CI) /median(IQR) | n | % (95% CI) /median (IQR) | P-value |
| Age (yrs)a | 1233 | 28 (22–34) | 448 | 29 (22–36) | 785 | 27.8 (22–33) | 0.004 |
| Ethnic groupb | 1247 | 457 | 790 | 0.021 | |||
| Sambaa | 34.0 (31.4–36.7) | 38.3(33.9–42.9) | 31.5 (28.4–34.9) | ||||
| Zigua | 32.5 (29.9–36.7) | 32.4 (28.2–36.8) | 32.5 (29.3–35.9) | ||||
| Othersb | 33.5 (30.9–36.2) | 29.3 (25.3–33.8) | 36.0 (32.7–39.4) | ||||
| Parityb | 1242 | 456 | 786 | 0.067 | |||
| 0 | 18.4 (16.4–20.7) | 18.4 (12.1–22.3) | 18.4 (15.9–21.)) | ||||
| 1 | 38.7 (36.1–41.5) | 35.5 (31.3–25) | 40.6 (37.2–31.4) | ||||
| 2 | 16.5 (14.5–18.7) | 16.0 (12.9–19.7) | 16.8 (14.3–19.6) | ||||
| 3 | 12.4 (10.7–14.4) | 12.3 (12.0–15.9) | 15.0 (12.5–14.8) | ||||
| >3 | 13.9 (12.1–16.0) | 17.5 (14.3–21.3) | 11.8 (9.8–14.3) | ||||
| House hold size (numbers)a | 1243 | 4.0 (3.6) | 457 | 4 (3–6) | 786 | 4 (3–6) | 0.31 |
| Education levelb | 1247 | 457 | 790 | 0.12 | |||
| No education | 8.1(6.7–9.8) | 9.0 (6.7–12.0) | 7.6 (5.9–9.7) | ||||
| Primary incomplete | 11.2 (9.5–13.1) | 11.4 (8.8–14.6 | 11.1(9.1–13.5) | ||||
| Primary school complete | 63.1(60.4–65.8) | 65.4 (60.9–69.7) | 61.8 (58.3–65.1) | ||||
| Secondary or higher | 17.6 (15.5–19.8) | 14.2 (11.3–17.7) | 19.5 (16.9–22.4) | ||||
| Occupationb | 1247 | 457 | 790 | 0.53 | |||
| Professional | 3.1(2.2–4.2) | 3.3 (2.0–5.4) | 2.9 (1.9–4.3) | ||||
| Business | 3.4 (2.6–4.6) | 3.5 (2.2–5.6) | 3.4 (2.4–4.9) | ||||
| Service provider | 15.2 (13.3–17.3) | 12.9 (10.1–16.3) | 16.6 (14.1–19.3) | ||||
| Farmer | 57.2 (54.4–59.9) | 59.1 (54.4–63.5) | 56.1 (52.6–59.5) | ||||
| House wife/student | 21.1(19.9–223.4) | 21.2 (17.7–25.2) | 21.0 (18.3–24.0) | ||||
| Type of house ownershipb | 1242 | 456 | 786 | 0.21 | |||
| Self/spouse built | 64.3 (61.6–67.0) | 66.5 (62.0–70.6) | 63.1 (59.7–66.4) | ||||
| Inherited | 15.7 (13.8–17.8) | 16.2 (13.1–19.9) | 15.4 (13.0–18.1) | ||||
| Rental | 20.0 (17.8–22.3) | 17.3(14.1–21.1) | 21.5 (18.8–24.5) | ||||
| Roofing materialsb | 1247 | 457 | 790 | 0.36 | |||
| Iron | 74.0 (71.0–76.3) | 73.3 (69.0–77.2) | 74.3 (71.1–77.2) | ||||
| Tin | 0.6 (0.3–1.3) | 0.2 (0.03–1.5) | 0.9 (0.4–1.8) | ||||
| Asbestos | 1.1(0.6–1.8) | 1.5 (0.7–3.2) | 0.9 (0.4–1.8) | ||||
| Thatch/mixed | 24.3 (22.0–26.8) | 25.0 (21.2–29.1) | 23.9 (21.1–27.0) | ||||
| Source of domestic water b | 1244 | 455 | 786 | 0.64 | |||
| Private tap | 7.7 (6.4–9.4) | 8.5 (6.3–11.5) | 7.2 (5.6–9.3) | ||||
| Private bore hole | 0.8 (0.4–1.5) | 1.1 (0.4–2.6) | 0.6 (0.3–1.5) | ||||
| Public tap | 53.7 (50.9–56.4) | 51.6 (47.0–56.2) | 54.6 (51.1–58.2) | ||||
| Public bore hole | 11.5 (9.9–13.4) | 11.0 (8.4–14.2) | 12.0 (9.7–14.3) | ||||
| River/pool | 26.3 (23.9–28.8) | 27.8 (23.9–32.1) | 25.6 (22.7–28.8) | ||||
| Type of toilet facilityb | 1246 | 456 | 790 | 0.38 | |||
| Flush | 25.0 (22.7–27.5) | 23.9 (20.2–28.1) | 25.7 (22.8–28.9) | ||||
| Pit | 74.1 (71.6–76.4) | 74.8 (70.6–78.6) | 73.7 (70.5–76.6) | ||||
| None | 0.9 (0.5–1.6) | 1.3 (0.6–2.9) | 0.6 (0.3–1.5) | ||||
| Socioeconomic statusb,b | 1235 | 453 | 782 | 0.25 | |||
| High | 33.5 (30.9–36.2) | 35.5 (31.2–40.1) | 32.3 (29.2–35.7) | ||||
| Medium | 33.4 (30.8–36.0) | 34.2 (30.0–38.7) | 32.9 (29.7–36.2) | ||||
| Low | 33.1 (30.5–35.8) | 30.2 (26.2–34.6) | 34.8 (31.5–38.2) | ||||
| Bed net ownership (Yes)b | 1247 | 78.8 (76.5–81.0) | 457 | 77.2 (72.3–80.9) | 790 | 79.7 (76.8–82.4) | |
| MUAC (cm) a | 1242 | 27.9 (25.8–31) | 453 | 27.4 (25.4–29.9) | 789 | 28 (26–31.5) | 0.0003 |
| Waist circumference (cm)a | 1218 | 80.0 (74.1–87.8) | 444 | 79.2 (74.2–86.1) | 774 | 80.3 (74–89) | 0.06 |
| Hip circumference(cm)a | 1234 | 94.5 (89–101.2) | 454 | 94 (88.1–99.5) | 780 | 95 (89.4–102.1) | 0.01 |
| Body mass index (kg/m2)a | 1231 | 22.7 (20.5–26.3) | 449 | 22.1 (20.2–25.2) | 782 | 23.0 (20.7–26.7) | 0.036 |
| Body mass index categories | |||||||
| Underweight | 1231 | 8.0 (6.6–9.7) | 9.4 (7.0–12.4) | 7.2 (5.7–9.3) | |||
| Normal weight | 60.5 (57.8–63.2) | 63.9 (59.4–68.2) | 58.9 (55.1–62.0) | ||||
| Overweight | 20.2 (18.1–22.6) | 18.0 (14.7–21.9) | 21.5 (18.7–24.5) | ||||
| Obesity | 11.2 (9.6–13.1) | 8.7 (6.4–11.7) | 12.7 (10.5–15.3) | ||||
| Previous use of hormone contraceptivesb | 1248 | 71.5 (68.9–73.9) | 458 | 32.5 (63.0–77.6) | 790 | 26.2 (23.2–29.4) | 0.017 |
| Length of menstrual periodsb | 1217 | 4 (3–5) | 446 | 4 (3–5) | 771 | 4 (3–5) | 0.104 |
| Length of menstrual cycle (days)b | 1162 | 428 | 734 | 0.144 | |||
| Normal (25–35) | 85.7 (83.6–87.6) | 84.1 (80.3–87.3) | 86.7 (84.0–88.9) | ||||
| Short (<25) | 2.9 (2.1–4.1) | 2.3 (1.2–4.3) | 3.3 (2.2–4.8) | ||||
| Long (≥35) | 11.4 (9.7–13.3) | 13.6 (10.6–17.1) | 10.0 (8.1–12.5) | ||||
| Self-reported malaria last 2 monthsb | 1234 | 22.7 (20.4–25.1) | 452 | 26.1(22.3–30.4) | 782 | 20.7 (18.0–23.7) | 0.029 |
| Malaria at enrolmentb | 1244 | 8.1 (6.7–9.8) | 456 | 10.3 (7.8–13.4) | 788 | 6.9 (5.3–8.8) | 0.032 |
| HIV seropositivee | 952 | 5.7 (4.4–7.3) | 344 | 9.0 (6.4–12.6) | 608 | 3.8 (2.5–5.6) | 0.004 |
| Intestinal helminths infestationsb | 434 | 3.0 (1.7–5.1) | 147 | 1.4 (0.3–5.4) | 287 | 4.9 (2.1–6.8) | 0.64 |
| Inflammation (CRP>5mg/L)b | 1229 | 15.2 (13.3–17.3) | 448 | 18.5 (15.2–22.4) | 781 | 13.3 (11.1–15.9) | 0.014 |
| Hemoglobin (g/dL)(mean±se) | 1248 | 12.2±0.04 | 458 | 10.7±0.06 | 790 | 13.1±0.03 | <0.001 |
| RBC morphological typesb | |||||||
| Normocytic-normochromic | 1248 | 56.3 (53.6–59.3) | 458 | 32.8 (28.6–37.2) | 790 | 70.0 (66.7–73.1) | <0.001 |
| Microcytic-hypochromic | 1248 | 17.5 (15.5–19.8) | 458 | 38.2 (33.9–42.8) | 790 | 5.6 (4.2–7.4) | |
| Microcytic-normochromic | 1248 | 19.9 (17.7–22.2) | 458 | 19.0 (15.6–22.9) | 790 | 20.4 (17.7–23.3) | |
| Normocytic-hypochromic | 1248 | 5.9 (4.7–7.4) | 458 | 9.8 (7.4–12.9) | 790 | 3.7 (2.6–5.2) | |
| Megaloblastic | 1248 | 0.3 (0.1–0.8) | 458 | 0.2 (0.03–1.5) | 790 | 0.4 (0.1–1.4) | |
| Micronutrient status | |||||||
| s-ferritin (μg/L)a | 1245 | 22.3 (10.1–39.7) | 457 | 11.3 (5.4–28.4) | 788 | 27.3 (15.2–43.8) | <0.001 |
| Iron deficiency b | 1226 | 37.6 (34.9–40.4) | 447 | 58.8 (54.2–63.3) | 779 | 25.4 (22.5–28.6) | <0.001 |
| s-Folate (nmol/L)a | 1194 | 30.8 (21–39.3) | 448 | 28.8 (19.7–37.8) | 746 | 32.2 (22.4–40.4) | 0.0003 |
| Folate deficiencyb | 1194 | 2.1 (1.4–2.9) | 448 | 3.1 (1.8–5.2) | 746 | 1.5 (0.8–2.6) | 0.043 |
| s-Vitamin B12(pmol/L)a | 1245 | 465.2 (343–613.4) | 457 | 455.8 (332.7–591.7) | 788 | 470.9 (347.7–626.8) | 0.07 |
| Vitamin B12 deficiencyb | 1245 | 0.6 (0.3–1.2) | 457 | 0.4 (0.1–1.7) | 788 | 0.6 (0.2–1.5) | 0.65 |
| Time from enrolment to conception (days)f | 259 | 87 (38–157) | 91 | 85 (32–143) | 168 | 91 (40–160) | 0.48 |
| Adverse pregnancy outcomesg | 249 | 34.1 (28.5–40.3) | 86 | 34.9 (25.4–45.7) | 163 | 33.7 (26.8–41.4) | 0.86 |
aMedian (IQR)
b Percentage (95% CI)
cOther ethnic group comprised of 56 minority groups that constituted <10% of the total study population per group.
dSocio-economic status was determined using principal components analysis based on woman education level, occupation, main source of domestic water, type of house ownership, roofing materials and type of toilet facility. Low scores for SES were given for no education/partial primary education, occupation as housewife/farmer, pond/river, rental housing, thatch roofing, or having no toilet.
e HIV infection was tested only for women who consented after voluntary counseling. Iron deficiency was based on Thurnhamet al. approach [26]. There were no mixed microcytic and macrocytic RBC morphological types.
f During the study period 259 women conceived and had gestational age estimated using ultrasound and data during pregnancy available. Women conceiving after the end of the study did not provide data for these analyses.
g Adverse pregnancy outcomes include miscarriage, low birthweight, prematurity, small for gestational age (<10thpercentile on the STOPPAM reference chart)[32] or stillbirth.
Abbreviations: Hb: Hemoglobin; MUAC: Mid-upper arm circumference; RBC: Red blood cell; CRP: C—reactive protein