We need iron to breathe, literally. It is a component of haemoglobin, which transports oxygen from the lungs via red blood cells to allow nutrients in other cells to convert into energy. Carbon dioxide is then transported back into the lungs and exhaled. It is also a component of myoglobin, which transports oxygen to the muscles. As pregnant women increase their blood volume by as much as 50%, their iron needs are greater than normal. Good sources of iron are liver, meat, beans and nuts. Spinach is a good source of iron, but raw, it contains an inhibitor called oxalic acid which prevents the iron content being absorbed. Cooked, the inhibitor is restricted, so the iron is more bioavailable.