Iron deficiency is the most common cause of anemia worldwide, according to the World Health Organization. Growing children and women are particularly affected, due to the increased demands of growth and to menstrual iron losses, respectively. Therefore, many pregnant women begin their pregnancies with marginal or decreased iron stores, and a growing fetus places further demands on maternal iron reservoirs. If you lack enough iron to produce new red blood cells, anemia is the inevitable consequence. Iron supplements are effective for preventing and correcting iron-deficiency anemia during pregnancy.
Anemia occurs if you have fewer red blood cells than normal or if the hemoglobin content of your red blood cells is abnormally low. Hemoglobin is the oxygen-carrying pigment found in healthy red blood cells, and iron is required for its synthesis. Symptoms of anemia include fatigue, weakness, poor exercise tolerance, lightheadedness, headache, shortness of breath, rapid pulse, leg cramps and poor mental function. An April 2011 review in "The Journal of Nutrition" reports that anemia during pregnancy increases the mortality risk for both mothers and their infants.
Many foods are good sources of iron. Oatmeal and other whole grains, red meats, liver, dried fruits, blackstrap molasses, beans, peas, seafood, dark green leafy vegetables, nuts and seeds all contain iron. However, morning sickness may limit your dietary iron intake, or you may have concerns about the safety of some foods, such as fish. Further, eating iron-rich foods may not furnish enough iron to correct serious cases of anemia. In these situations, iron supplements are often needed.
The iron supplement most commonly prescribed by physicians for pregnant women is ferrous sulfate, which is a cheap, reasonably well-absorbed form of iron. It is also the form most likely to cause side effects, such as stomach irritation and constipation. Dr. Elson Haas, author of "Staying Healthy with Nutrition," believes that ferrous gluconate or fumarate, also inexpensive iron sources, are absorbed as well as ferrous sulfate and cause fewer side effects. The best iron supplements, says Haas, are "chelated" forms of iron, such as ferrous succinate or aspartate.
Doses and Effectiveness
The form and dosage of iron you take during pregnancy depends largely on your doctor's preferences and the severity of your anemia. Haas recommends 50 mg of a chelated iron supplement once or twice daily to address most needs of pregnancy. Alternatively, your physician may opt for 325 mg of ferrous sulfate or ferrous gluconate, taken 2 to 3 times daily. Typically, your iron stores will be replenished and your blood count will improve within 4 to 6 weeks of starting your iron supplement.