Anaemia happens when the blood has insufficient red cells, or when red cells carry insufficient haemoglobin to deliver adequate oxygen to the tissues. Haemoglobin levels change in pregnancy with a normal reduction at the beginning of pregnancy and a slight rise towards the end of pregnancy. Anaemia in pregnancy can be mild, moderate or severe, and women are offered different treatments according to their level of anaemia and the possible cause. Anaemia can be caused by a range of factors including certain diseases or a shortage of iron, folic acid or vitamin B12. The most common cause of anaemia in pregnancy is due to iron shortage. Iron treatment can be given by mouth, or an injection into the muscle (intramuscular) or into the vein (intravenous), or by giving a blood transfusion. In this review we identified 17 randomised controlled trials involving over 2500 women. However, many treatment variations were studied leaving rather small study populations for each treatment and, therefore, imprecise estimates that make it difficult to draw conclusions
on the effects of treatment on women with different degrees of anaemia. Amongst the complications of iron treatments, we found that intravenous treatment may cause venous thrombosis (blockages in the veins) and the intramuscular treatment caused important pain and discolouration at the injection site; but it is unclear if women and babies are healthier when women are given iron for anemia during pregnancy. It also remains unclear what the effects of treatments given by different routes and in different populations are; therefore, it is not possible to draw a well-informed balance of benefits and harms for the differing levels of severity of anaemia. This would be better addressed if a few frequently-used treatments were compared in a multicenter randomised controlled trial involving women from different backgrounds and settings, and this study was big enough to respond to these questions in a valid way.