When selecting a form of iron for our +mum dietary supplement, we chose ferrous bisglycinate for its high bioavailability and gastrointestinal tolerance. It is a neutral molecule that does not break down in gastric acid – it is delivered intact to the intestine, where it is easily absorbed. Other types of iron have low bioavailability and often produce unpleasant gastrointestinal side effects, such as nausea, constipation and stomach upset. In addition, ferrous bisglycinate is easier to absorb and less likely to block the absorption of other nutrients, such as vitamin E and calcium. Iron is the basic carrier of oxygen in the blood in the form of haemoglobin and the facilitator of oxygen storage in the muscles in the form of myoglobin. Pregnant women need two to three times more iron than non-pregnant women. Iron supplementation during pregnancy protects against pregnancy-induced anaemia, a condition in which you don’t have enough red blood cells to carry oxygen around your body. Some studies have shown that anaemia during pregnancy increases the risk of haemorrhage in the mother and the likelihood of having a low-birth-weight baby. Research on children with iron deficiency anaemia has shown an increased risk of neurocognitive development problems.