Summary of findings for the main comparison. (Infant outcomes) Any supplements containing iron compared with same supplements without iron or no treatment/placebo (no iron or placebo) for pregnant women.
| (Infant outcomes) Any supplements containing iron compared with same supplements without iron or no treatment/placebo (no iron or placebo) | ||||
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Patient or population: Pregnant women of any gestational age and parity Setting: Hospital or community‐based antenatal clinics Intervention: Any supplements containing iron Comparison: Same supplements without iron or no treatment/placebo (no iron or placebo) | ||||
| Outcomes | Relative effect (95% CI) | No of Participants (studies) | Quality of the evidence (GRADE) | Comments |
| Low birthweight (less than 2500 g) (ALL) | RR 0.84 (0.69 to 1.03) | 17,613 (11 RCTs) | ⊕⊕⊝⊝ low 1,2 | |
| Birthweight (g) (ALL) | The mean birthweight (g) (ALL) in the intervention group was 23.75 higher (3.02 lower to 50.51 higher) | 18,590 (15 RCTs) | ⊕⊕⊕⊝ moderate 1 | |
| Preterm birth (less than 37 weeks of gestation) (ALL) | RR 0.93 (0.84 to 1.03) | 19,286 (13 RCTs) | ⊕⊕⊕⊝ moderate 1 | |
| Neonatal death (within 28 days after delivery) (ALL) | RR 0.91 (0.71 to 1.18) | 16,603 (4 RCTs) | ⊕⊕⊝⊝ low 1,2 | |
| Congenital anomalies (ALL) | RR 0.88 (0.58 to 1.33) | 14,636 (4 RCTs) | ⊕⊕⊝⊝ low 1,2 | |
| CI: Confidence interval; RR: risk ratio | ||||
| GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate. | ||||
1Several studies contributing data had design limitations
2Wide 95% CI crossing the line of no effect