Summary of findings 2. (Maternal outcomes) Any supplements containing iron compared with same supplements without iron or no treatment/placebo (no iron or placebo) for pregnant women.
| (Maternal outcomes) Any supplements containing iron compared with same supplements without iron or no treatment/placebo (no iron or placebo) | ||||
| Patient or population: Pregnant women of any gestational age and parity Settings: 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 |
| Maternal anaemia at term (Hb less than 110 g/L at 37 weeks' gestation or more) (ALL) | RR 0.30 (0.19 to 0.46) | 2199 (14 RCTs) | ⊕⊕⊝⊝ low 1,2 | |
| Maternal iron deficiency at term (as defined by as defined by trialists, based on any indicator of iron status at 37 weeks's gestation or more) (ALL) | RR 0.43 (0.27 to 0.66) | 1256 (7 RCTs) | ⊕⊕⊝⊝ low 2,3 | |
| Maternal death (death while pregnant or within 42 days of termination of pregnancy) (ALL) | RR 0.33 (0.01 to 8.19) | 12,560 (2 RCTs) | ⊕⊝⊝⊝ very low 4,5 | |
| Side effects (any reported throughout the intervention period) (ALL) | RR 1.29 (0.83 to 2.02) | 2423 (11 RCTs) | ⊕⊝⊝⊝ very low 2,3,6 | |
| Maternal severe anaemia at any time during second and third trimester (Hb less than 70 g/L) (ALL) | RR 0.22 (0.01 to 3.20) | 2125 (9 RCTs) | ⊕⊝⊝⊝ very low 3,6,7 | |
| Infection during pregnancy (including urinary tract infections) (ALL) | RR 1.21 (0.33 to 4.46) | 727 (1 RCT) | ⊕⊕⊝⊝ low 5 | |
| 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 and one had serious design limitations
2High heterogeneity I² > 80%
3Several studies contributing data had design limitations
4One of the studies contributing data had design limitations
5Wide 95% CI crossing the line of no effect. Low event rate
6Wide 95% CI crossing the line of no effect
7High heterogeneity I² = 69%