In this review, we identified 23 trials involving 3198 pregnant women. Many of the trials were in low‐income countries and many treatment variations were studied. Oral iron reduced the incidence of anaemia but is known to sometimes cause constipation and nausea. Although the intramuscular and intravenous routes produced better levels of red cells and iron stores than the oral route, no clinical outcomes (such as pre‐eclampsia, preterm births, postpartum haemorrhage) were assessed and there were insufficient data on adverse effects. Intravenous treatment can cause venous thrombosis (blockages in the veins) and intramuscular treatment causes important pain and discolouration at the injection site. It was unclear if women and babies were healthier when women were given iron for mild or moderate anaemia during pregnancy. There were no studies on using blood transfusions.