The quality of evidence is downgraded by study quality (unclear allocation concealment, blinding, incomplete outcome data, and selective reporting) and heterogeneity.
A Cochrane review «Daily oral iron supplementation during pregnancy»1 «Finkelstein JL, Cuthbert A, Weeks J, et al. Daily oral iron supplementation during pregnancy. Cochrane Database Syst Rev 2024;8(8):CD004736. »1 included 57 studies with a total of 48 971 subjects. The trials were conducted in 27 countries around the world and many studies were conducted in countries that had some malaria risk in parts of the country. There were significant heterogeneity across most prespecified outcomes. Low birthweight was reduced (RR 0.84, 95% CI 0.72 to 0.99; 12 trials, n=18 290) with iron supplements compared to controls. Babys were slightly heavier (mean difference 25g), but this was non-significant. There were no clear differences between groups for neonatal death, preterm birth, or congenital anomalies. Maternal anaemia (Hb less than 110 g/L) at term was reduced (RR 0.30; 95% CI 0.20 to 0.40; 14 trials, n=13 543, low certainty evidence).