Women need extra iron when they are pregnant to keep their blood and that of their babies rich with oxygen. Iron in the blood helps prevent anemia. Most prenatal vitamins contain enough iron for pregnant women; however, some women choose other supplements that also contain this vital mineral. If you use iron supplements, be sure to avoid passing the upper limits as this can cause iron toxicity.
Iron in Prenatal Vitamins
Most prenatal multivitamin supplements contain enough iron to meet a pregnant woman's daily needs. The average pregnant woman needs around 27 mg of iron daily. Getting enough iron from your diet alone can be a challenge, considering that you needed about a third less this amount before you became pregnant. Fortunately, most women taking prenatal supplements are already a leg up, as they can fall back on the iron in their vitamin when their diets run short. Some women prefer to supplement their prenatal with additional iron; however, when doing so they should take care to avoid iron toxicity.
Iron Toxicity
The body excretes very little iron. When taken in excess, iron begins to build up in the blood and accumulates in the body's tissues and organs. While it is more common among older adults, pregnant women who overload on iron can potentially risk iron toxicity. Unfortunately, iron toxicity is not always easy to diagnose: the signs may not be immediate, and may not even appear until after damage has been done. Some women may experience diarrhea or a decrease in their urine output. Others may notice their body temperature is lower than normal. If left untreated, iron toxicity can lead to organ damage -- particularly liver damage. To reduce your risk of iron toxicity, be sure to avoid exceeding the upper recommended limits of iron during your pregnancy.
Iron's Upper Limits
The National Institutes of Health Office of Dietary Supplements estimates the upper limits of safe iron consumption to be about 45 mg daily for pregnant women. This number is not set in stone: it serves as a guideline for women supplementing without a physician's guidance. It may be safe for a pregnant woman to go above and beyond this amount if, and only if, her body will use all of it. Pregnant women with anemia, or those with higher iron needs than the average woman, may require more than this.
Iron in Food: Risky?
Suppose you are taking a prenatal supplement that contains 30 mg of iron, you eat a particularly iron-rich diet and you are not anemic. Should you worry about iron toxicity? Probably not. Synthetic supplements contain a higher concentration of vitamins and minerals than you find in your food. It is rare to overdose on even fat soluble supplements through your prenatal vitamin and food alone. So don't worry if you get a craving for steak: you can have an iron supplement and eat it too.
References
- American Congress of Obstetricians and Gynecologists: Nutrition During Pregnancy
- American Pregnancy Association: Prenatal Vitamins: How Much is Too Much?
- National Institutes of Health Office of Dietary Supplements: Dietary Supplement Fact Sheet: Iron
- Cornell University Department of Animal Science: Iron Toxicity, What You Don't Know
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