Table 4.
Effect of iron supplementation versus placebo on perinatal outcomes.a
| Outcome | Iron | N | Placebo | N | Relative Risk (95% CI) | P Value |
|---|---|---|---|---|---|---|
| Fetal lossb no. (%) | 56 (7.7) | 731 | 45 (6.1) | 738 | 1.26 (0.86, 1.92) | 0.24 |
| Infant mortality at 6 weeks no. (%)c | 20 (3.0) | 675 | 16 (2.3) | 692 | 1.28 (0.67, 2.45) | 0.45 |
| Birthweight | 3155 (545)a | 672 | 3137 (519) | 691 | 0.89 | |
| < 2500 g – no. (%) | 45 (6.7) | 672 | 51 (7.4) | 691 | 0.91 (0.62, 1.34) | 0.62 |
| < 2000 g – no. (%) | 15 (2.2) | 672 | 14 (2.0) | 691 | 1.10 (0.54, 2.26) | 0.79 |
| Gestational age at delivery – weeks | 39.3 (2.5) | 665 | 39.2 (2.7) | 685 | 0.37 | |
| Preterm birth – no. (%)b | ||||||
| < 37 weeks | 100 (15.0) | 665 | 113 (16.5) | 685 | 0.91 (0.71, 1.17) | 0.46 |
| < 34 weeks | 21 (3.2) | 665 | 27 (3.9) | 685 | 0.80 (0.46, 1.40) | 0.44 |
| Low birthweight and preterm birth – no. (%)d,e | 27 (4.1) | 665 | 21 (3.1) | 685 | 1.32 (0.76, 2.32) | 0.32 |
| Low birthweight and term birth – no. (%)d,e | 18 (2.7) | 665 | 30 (4.4) | 685 | 0.62 (0.35, 1.10) | 0.10 |
| Small for gestational age – no. (%)d,f | 121 (18.0) | 672 | 125 (18.1) | 691 | 1.00 (0.79, 1.25) | 0.97 |
| Small for gestational age (INTERGROWTH)g | 101 (15.8) | 641 | 105 (16.2) | 648 | 0.97 (0.76, 1.25) | 0.83 |
a
Mean (SD) for continuous variables.
b
Stillbirth and miscarriage
c
Live birth only
d
Restricted to births at 21 to 44 weeks gestation.
e
Low birthweight defined as < 2500 g.
f
Small for gestational age was defined as birth weight below the 10th percentile for gestational age using the Alexander standard27.
g
Small for gestational age was defined as birth weight below the 10th percentile for gestational age using the INTERGROWTH standard28, restricting to births 30 to 42 weeks gestation.