Feature Articles

Women & Anemia: Increased Need for Iron During Pregnancy

September 19, 2008
This three part series on Women & Anemia discusses a few common causes of anemia unique to women, including heavy menstrual bleeding, pregnancy and child delivery. Part 2 focuses on iron deficiency anemia during pregnancy. Part 1 | Part 3

During pregnancy, a woman’s body undergoes many changes in order to provide for the needs of her growing baby. Some of these physical changes are very obvious, such as changes in body shape and size, while some changes are much less apparent. Changes in the mother’s blood is one of these less noticeable, but important changes.

Pregnant mother caressing her belly

Most anemia during pregnancy results from an increased need for iron. It is estimated that women will need approximately 50% more iron during pregnancy; increasing from 18 to 27 milligrams (mg) per day.1 A mother and baby need more iron for a few different reasons. As the mother’s body grows, the amount of blood in her body also grows, especially in the last three months of pregnancy. During this time she will have as much as 50% more blood in her body. To produce more red blood cells, the mother’s body will need additional iron to make hemoglobin, the part of the red blood cell that carries oxygen. Also, the growing baby takes all the iron it needs from mom, regardless of how much she has available in her system. Towards the end of pregnancy the baby will be storing iron for his or her first six months of life. Because of these changes and other changes like these, some women may develop anemia during their pregnancy.

Pregnant women may be at an increased risk for anemia if you:

  • Have morning sickness severe enough to cause frequent vomiting
  • Have had more than 2 pregnancies close together
  • Are pregnant with more than one baby
  • Have an iron-poor diet
  • Had a heavy pre-pregnancy menstrual flow

The consequences of anemia during pregnancy extend beyond simply feeling tired and weak. Pregnant women who are anemic have an increased risk for problems when their baby is born, particularly if they are anemic in the first trimester. According to Dr. Arnold Friedman, Chairman of Obstetrics and Gynecology at Beth Israel Medical Center in New York, Quote: “Women who start their pregnancy with low stored iron are more likely to become anemic during the course of the pregnancy.” – Dr. Arnold Friedman “Approximately 5% of women lose excess blood during childbirth. If a mother is anemic during her pregnancy, she is much more likely to need a blood transfusion following childbirth.” Additionally, current research shows that babies born to mothers suffering from anemia may not be able to store enough iron before birth, are more likely to be born prematurely, and have lower birth weights. This lack of stored iron may continue well into the baby’s first year of life.2

Unfortunately, many women start pregnancy without sufficient stored iron to meet their body's increased demands. Dr. Friedman stated, “Women who start their pregnancy with low stored iron are more likely to become anemic during the course of the pregnancy.” All women of childbearing age regularly lose blood during menstruation. If their diet does not contain enough iron to replace what is lost every month, their stored iron becomes depleted. As pregnancy exhausts the already depleted iron, the mother no longer has enough iron to make the hemoglobin she needs, and she becomes anemic. Because so many women do have low stored iron, it is has become standard practice to be evaluated for anemia at your first prenatal appointment.

A Well-Balanced Diet and Iron Supplements

Pregnant women should:

  • Get tested for anemia at your first prenatal appointment
  • Eat a nutritious iron-rich diet
  • Take a daily prenatal vitamin containing at least 30mg of iron
  • Let your doctor know if you are experiencing symptoms of anemia

While you’re pregnant, it is extremely important to eat a well-balanced meal. Even then it is difficult to get the recommend 27mg of iron a day since even nutritious diets only provide you with about 12-14mg of iron. In order to avoid iron deficiency, it is often necessary for pregnant women to take iron supplements. The Centers for Disease Control and Prevention (CDC) recommends that all pregnant women take a daily supplement of 30mg of elemental iron as a preventive dose.

A majority of prenatal vitamins contain 30mg of iron, so be sure to take your vitamins. Pregnant women who are diagnosed with iron deficiency anemia are usually advised to take a total dose of at least 120mg of iron each day. If so, your doctor may recommend an iron supplement in addition to your prenatal vitamin.4 If you think you may have anemia, we recommend you talk to your healthcare professional. See the basic questionnaire called the Symptoms Quiz, which you can fill out and take to your doctor or gynecologist.

Read the full series on Women & Anemia. Part 1: Heavy Menstrual Bleeding | Part 3: Child Delivery


  1. Milman N, Bergholt T, Byg KE, Eriksen L, Graudal N. Iron status and iron balance during pregnancy. A critical reappraisal of iron supplementation. Acta Obstet Gynecol Scand. 1999 Oct;78(9):749-57.
  2. Allen LH. Anemia and iron deficiency: effects on pregnancy outcome. Am J Clin Nutr. 2000 May;71(5 Suppl):1280S-4S.
  3. Earle R, Woteki CE, eds. Iron Deficiency Anemia: Recommended Guidelines for the Prevention, Detection, and Management Among U.S. Children and Women of Childbearing Age. Institute of Medicine, National Academy Press; 1993.
  4. Stoltzfus R, Dreyfuss. Guidelines for the use of iron supplements to prevent and treat iron deficiency anemia. International Nutritional Anemia Consultative Group. Washington DC: ILSI Press. Link.
  5. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 95: anemia in pregnancy. Obstet Gynecol. 2008 Jul;112(1):201-7.
  6. Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium and Zinc. Washington, DC: National Academy Press, 2001. Link.