When it comes to iron in pregnancy, it’s very important to get the balance right. Midwife Esther Calje explains.
Whilst iron deficiency and iron deficiency anaemia (IDA) are common problems in pregnancy, they are often not managed well. What is it that makes levels so hard to master? And how do pregnant women get the balance right?
Iron is the most abundant element on our planet, and as a trace element, it is vital for human life. Iron is not only essential to make haemoglobin, the protein that delivers oxygen to the body in our blood, but it's also important for all cell growth and body systems: for heat and energy production, for the immune and musculo-skeletal systems, and for brain development and function. No wonder we feel physically and mentally tired when we don’t have enough! Iron within the body, however, is carefully regulated. High levels can be harmful. So too much iron can be problematic, but demands in pregnancy are extraordinarily high, and most women do not have sufficient iron stores to meet those needs.
In high demand
The demand for iron during pregnancy increases because of the remarkable changes and growth that women’s bodies undergo. In early pregnancy, a healthy woman’s blood volume increases with approximately 30% more red blood cells and 50% more fluid. This results in a normal drop in haemoglobin levels (also called physiological anaemia), as the red blood cells become diluted compared to pre-pregnancy. Iron is required to grow a healthy placenta that, in turn, nourishes the growing baby. Most iron is transferred to the baby by the placenta from thirty weeks gestation, even when the woman herself has low iron levels.
The most common symptom of anaemia is fatigue, but this can be difficult to distinguish from the normal tiredness of pregnancy. This is why it is important to get your blood tested early by your midwife or doctor. Other symptoms that women experience include lethargy, irritability, pale skin, palpitations, dizziness and shortness of breath. Anaemia and iron deficiency are also associated with postnatal depression, increased likelihood of blood transfusion, increased risk of infection, difficulties with bonding and breastfeeding, reduced newborn iron levels, and developmental delays in infants. Severe anaemia in pregnancy is associated with low birth weight and premature birth.
Staying on top
The best way to prevent IDA is an iron-rich diet from haem and non-haem sources. Haem iron, from red meat such as beef and lamb, not only gives you plenty of iron when eaten three to four times a week, but it also helps the absorption of non-haem iron. Chicken and fish and freshly cooked hot mussels are also good sources of haem iron. Green leafy vegetables, tofu, beans, wholegrain breads, dried fruit and some cereals are all good sources of non-haem iron. Interestingly, cooking in cast iron cookware also increases iron intake, and eating one or two pieces of fresh fruit after a meal will improve the absorption of haem and non-haem iron. Another important way to maximise absorption is to avoid things that bind to iron, such as tannins in tea, coffee and red wine, an hour or two before and after meals. Calcium, magnesium and phytates also bind to iron, inhibiting absorption. The Ministry of Health recommend a daily intake of 27mg of iron during pregnancy. However, even with an iron-rich diet and the natural increase in iron absorption during pregnancy, diet alone is insufficient to meet iron requirements by the third trimester. Iron requirements can only be met if there are adequate iron stores from early pregnancy.
Too much iron can be harmful, especially if women are already iron replete, or have an undiagnosed iron metabolism disorder resulting in iron overload. Supplementing pregnant women who are iron replete with high doses of iron is associated with increased blood pressure and blood viscosity (thickness), and decreased blood flow to the placenta, affecting foetal growth. Iron is also toxic to children – a few tablets for a small child can be fatal. So approach iron carefully, and store lolly-like iron tablets out of reach.