Your iron requirements go up significantly when you're pregnant. Iron is essential for making hemoglobin, the protein in red blood cells that carries oxygen to other cells. During pregnancy, the amount of blood in your body expands until you have almost 50 percent more than usual. And you need more iron to make more hemoglobin for all that additional blood. You also need extra iron for your growing baby and placenta.
Unfortunately, most women start pregnancy without sufficient stores of iron to meet their body's increased demands particularly in the second and third trimesters. If you get to the point that you no longer have enough iron to make the hemoglobin you need, you become anemic.
Your risk is even higher if you have morning sickness severe enough to cause frequent vomiting, if you've had two or more pregnancies close together, if you're pregnant with more than one baby, if you have an iron-poor diet, or if your pre-pregnancy menstrual flow was heavy.
This is why the amount of iron you need shoots up during pregnancy from 18 to 27 milligrams (mg) a day. And because it's hard to get enough iron through diet alone, the Centers for Disease Control recommend that pregnant women take a daily supplement of 30 mg of elemental iron as a preventive dose. Many prenatal supplements contain that amount.
Iron deficiency is the most common cause of anemia, but it's not the only cause. You could also develop anemia by not getting enough folic acid or vitamin B12, by losing a lot of blood, or from certain diseases or inherited blood disorders such as sickle cell disease. The treatment for anemia depends on the cause. Iron supplements are not always the answer.
Your practitioner tests your blood for anemia at your first prenatal appointment. One of these tests (hematocrit) measures the percentage of red blood cells in your plasma. The other (hemoglobin) measures the number of grams of hemoglobin in your blood. It's more common to develop anemia as your pregnancy progresses, however, so you'll have another blood test in your late second trimester or early third trimester. It's normal for your hemoglobin and hematocrit levels to go down somewhat in the second half of pregnancy, when the amount of blood in your body is expanding dramatically and the amount of plasma (the fluid component of blood) increases faster than the number and size of red blood cells — but you don't want them to dip too low.
If you do develop anemia, you might not have any symptoms at all, especially if your condition is mild. Or you might feel tired, weak, and dizzy. (Of course, these are symptoms that many women have anyway during pregnancy, anemic or not.) You might also notice that you're paler (especially in your fingernails, the underside of your eyelids, and your lips) and have a rapid heartbeat, heart palpitations, shortness of breath, or trouble concentrating. Finally, some studies have found a link between severe iron-deficiency anemia and cravings for non-food substances such as ice, paper, or clay (a condition known as pica). If you do have these cravings, don't give in to them, and be sure to tell your healthcare provider.
Your baby does a good job taking care of his iron needs — he'll get his share before you do. If you remain anemic during the first two trimesters, though, you're at a higher risk for having a preterm delivery or a low-birthweight baby, so it is something to take seriously. And if you're severely deficient, it could affect your baby's iron stores at birth, increasing his risk for anemia later in infancy.
Iron-deficiency anemia affects your health as well. It can sap your energy and make it harder for your body to fight infection. And if you're anemic later in pregnancy, you're more likely to have problems if you lose a lot of blood when you give birth. You may feel dizzy, have a rapid heart rate, or have other symptoms that require you to stay in the hospital an extra day or two. You're also more likely to need a blood transfusion.
Calcium interferes with your body's ability to absorb iron. So if you're taking calcium supplements, or an antacid that contains calcium, don't take either one while you're eating iron-rich foods or at the same time as your iron supplement. For the same reason, don't take your supplement with milk, which is rich in calcium. Drink milk between meals, instead. The same goes for tea and coffee, which contain polyphenols that interfere with the absorption of iron from supplements and plant sources.
Eating or drinking something rich in vitamin C at the same time you take your iron supplement or eat iron-rich plant foods can help your body absorb significantly more of the type of iron found in non-animal sources. Good vitamin C choices include a glass of orange or tomato juice, a handful of strawberries, sweet (bell) peppers, or half a grapefruit. Meat and fish (sources of heme iron, which your body absorbs much more easily) can also improve your absorption of the iron in non-meat foods. For example, putting a bit of beef in a pot of vegetable chili can help you absorb iron from the vegetables.
If your test indicates that you're anemic, your practitioner will prescribe an iron supplement of 60 to 120 mg a day or more. To make sure you absorb as much of the iron as possible, take your iron pills on an empty stomach. Wash them down with water or orange juice (the vitamin C helps with absorption) but not with milk (calcium hinders absorption).
Note that these doses refer to the amount of "elemental iron," or pure iron, in a supplement. Some labels list the amount of ferrous sulfate (a kind of iron salt) instead of or in addition to the amount of elemental iron. A supplement that contains 325 mg of ferrous sulfate will give you about 60 mg of elemental iron. Others use ferrous gluconate, 300 mg of which yields about 34 mg of elemental iron.
One more important thing to note: Be vigilant about keeping any pills containing iron in childproof containers and away from children. More kids die from iron overdose each year than from any other kind of accidental drug poisoning. In fact, a single adult dose can poison a small child.