Iron is an essential mineral in the production of red blood cells. During pregnancy, your blood volume increases nearly 50 percent, putting excessive demands on your body’s ability to produce vital red blood cells. Your fetus also has specific iron requirements, especially during the last months of pregnancy, when iron stores are building up. When you are not pregnant you need 18 milligrams of iron a day. When you are pregnant, you need 27 milligrams to prevent a deficiency.
If you’re not meeting your increased iron needs during pregnancy, your fetus will draw its supply from your iron stores, leaving you anemic and exhausted. Anemia is caused by a decline in the amount of hemoglobin in the blood. Hemoglobin is a protein found in red blood cells and it plays a very important role in carrying oxygen throughout your body. To build up hemoglobin concentrations, you need more iron to help increase the production of red blood cells. Normally, you can meet most of your daily iron needs by following a balanced diet. However, because of the increased demands of pregnancy, it is almost impossible to maintain your iron stores through diet alone. This is why many nutritionists and doctors recommend that women take a special prenatal vitamin supplement throughout their pregnancy. These supplements provide extra iron as well as calcium and folic acid (more on these nutrients later).
If you have anemia, you will feel tired, weak and light-headed. You may also experience shortness of breath and heart palpitations. Anemia develops most often after the 20th week of pregnancy and is identified through blood tests that measure your hemoglobin levels. Your doctor may recommend that you take iron supplements throughout the second half of your pregnancy to avoid developing iron-deficiency anemia.
If you are diagnosed with iron-deficiency anemia, be sure to read chapter 3, “Anemia.” In this chapter I discuss your recommended daily intake, the best food sources of iron and how to enhance your body’s absorption of this mineral.
Fairly early in your pregnancy, your blood will be tested for Rhesus (Rh) factor. Rh factor is a type of protein that is sometimes present on red blood cells. You are Rh-positive if you have the protein and Rh-negative if you don’t. Your Rh factor is inherited from your parents and is determined by your genes. If your blood is Rh-positive and your partner’s blood is Rh-negative, there is a chance that your baby may inherit Rh-negative genes. When your Rh factor is not compatible with that of your fetus, your immune system will respond by producing antibodies that recognize your baby as a foreign substance in your body. The blood of your first Rh-positive baby will trigger the antibodies. When you become pregnant with a second Rh-negative baby, these antibodies will attack and destroy the fetus’s red blood cells, resulting in fatal fetal anemia. To prevent your immune system from producing antibodies, you will be given an injection of Rh immunoglobulin that will destroy the Rh-positive cells in your body. When detected through proper prenatal care, this life-threatening condition is now very rare.