For maternal outcomes, there was no clear evidence of differences between groups for anaemia at term (average RR 1.22; 95% CI 0.84 to 1.80; participants = 676; studies = four; I² = 10%; very low quality). Women receiving intermittent supplementation had fewer side effects (average RR 0.56; 95% CI 0.37 to 0.84; participants = 1777; studies = 11; I² = 87%; very low quality) and were at lower risk of having high haemoglobin (Hb) concentrations (greater than 130 g/L) during the second or third trimester of pregnancy (average RR 0.53; 95% CI 0.38 to 0.74; participants = 2616; studies = 15; I² = 52%; (this was not a primary outcome)) compared with women receiving daily supplements. There were no significant differences in iron-deficiency anaemia at term between women receiving intermittent or daily iron + folic acid supplementation (average RR 0.71; 95% CI 0.08 to 6.63; participants = 156; studies = one). There were no maternal deaths (six studies) or women with severe anaemia in pregnancy (six studies). None of the studies reported on iron deficiency at term or infections during pregnancy.