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Forest plot of age subgroup. (a) Weighted mean difference (WMD) forest plots of changes in haemoglobin (g/l) concentrations. (b) WMD forest plots of studies estimating changes in serum ferritin (μg/l) concentrations. Horizontal lines=95% CI. The size of the data marker corresponds to the weight of that study. The diamond and vertical broken line represent the summary estimate. The result favours experimental groups.
