Beyond the Prenatal: Do You Need An Iron Supplement During Pregnancy?

The amount of blood in your body increases by up to 50% when you’re pregnant. This ensures there’s enough blood and nutrients reaching your growing baby. One nutrient that’s especially important during pregnancy is iron.

Getting too little iron during pregnancy can lead to iron-deficiency anemia. This type of anemia (a condition of low blood cells) occurs when you don’t have enough iron. This can put your baby at risk of preterm delivery and low birth weight. So even though iron is part of most prenatal vitamins, do you need an additional iron supplement during pregnancy? And what dose should you take?

Why is iron important?

Iron is an essential mineral for everyone. This is because iron helps your body make hemoglobin (a protein in your red blood cells). Hemoglobin helps carry oxygen from the lungs to the rest of the body. Iron also helps your body make myoglobin, a protein that helps deliver oxygen to your muscles. 

If your iron levels are low, you may develop iron-deficiency anemia. This can cause a variety of symptoms like weakness, tiredness, and trouble concentrating.

Iron becomes even more important during pregnancy. In addition to the mother’s iron needs, there’s a growing baby that requires iron too. 

How much iron do I need during pregnancy?

During pregnancy, you need more iron than you normally do. Non-pregnant adult women need 18 mg/day of iron. But pregnant women need 27 mg/day.

There are three main reasons you need more iron during pregnancy:

1. You have a larger amount of blood during pregnancy. More blood means you have more red blood cells. And red blood cells need iron to do their job. 

2. Your baby needs iron. During pregnancy, you have a growing baby that needs iron. In fact, your baby will store iron in the womb to use in the first six months after birth.

3. The placenta has iron needs, too. The placenta is an organ that develops during pregnancy. Your growing baby is reliant on the placenta to provide it with nutrients. During pregnancy, the placenta stores iron to protect the baby in case the mother has a low iron supply.

Do I need an iron supplement during pregnancy?

Not necessarily. It’s generally recommended that all pregnant women in the U.S. take a prenatal vitamin with iron and eat an iron-rich diet. Whether you need an additional iron supplement will depend on your iron levels.

But experts don’t always agree on the specifics of iron supplementation during pregnancy. A few organizations have differing views:

• American College of Obstetricians and Gynecologists (ACOG): ACOG recommends taking a prenatal vitamin with iron during pregnancy. Along with a healthy diet, this may be enough to meet your iron needs. ACOG doesn’t specify how much iron should be in your prenatal vitamin.

• World Health Organization (WHO): WHO recommends a daily iron supplement of 30 to 60 mg. This could be in your prenatal vitamin, or provided through a separate iron supplement.

• U.S. Preventive Services Task Force (USPSTF): USPSTF states there's not enough research to recommend routine iron supplementation in all pregnant women. They believe that studies are conflicting on whether all pregnant women — including those with normal iron levels — need routine iron supplementation.

Despite these varied recommendations, your OB-GYN will likely recommend you take a prenatal vitamin with iron and eat an iron-rich diet. Make sure to check the label of your prenatal vitamin to see if it contains iron. Many prenatal vitamins do, but some don’t. 

Your OB-GYN will also likely run blood tests to check for anemia during pregnancy. If you're found to have iron-deficiency anemia, they may recommend adding an iron supplement in addition to your prenatal vitamin with iron. But make sure you get the OK from your OB-GYN before adding an iron supplement. 

Additionally, you shouldn’t increase the dose of your prenatal vitamin to make up for an iron deficiency. This will increase your intake of all the vitamins in the prenatal, which can be dangerous.

Why is low iron in pregnancy dangerous?

Because iron plays a major role in many bodily functions, untreated iron deficiency can have negative effects for the mother. Examples include:

• Preeclampsia

• Higher risk of infection

• Organ damage due to lack of oxygen

• Heart problems, including arrhythmias or heart failure

• A weaker immune system

Your growing baby may also have complications as a result of not getting enough iron. Some studies have shown that babies who don’t get enough iron are more likely to be born premature or at a low birth weight. 

What are symptoms of low iron in pregnancy?

You may not always feel symptoms of low iron, especially at first. But if low iron levels aren’t corrected, iron-deficiency anemia can occur. Signs and symptoms of iron-deficiency anemia include:

• Shortness of breath

• Tiredness

• Weakness

• Hair loss

• Leg cramping

Some symptoms of low iron can mimic symptoms of pregnancy itself. However, if you have any ongoing symptoms of iron-deficiency anemia, talk to your healthcare provider. They may consider doing a blood test to check for low iron.

How can I keep my iron levels up during pregnancy?

You can keep up your iron levels in pregnancy by eating iron-rich foods and taking your prenatal vitamins with iron daily. These two actions may prevent you from needing an additional iron supplement. If your preferred prenatal vitamin doesn’t have iron, talk to your healthcare provider about whether you need an additional iron supplement.

Best food sources of iron during pregnancy

Iron comes in two forms: heme iron and non-heme iron. Heme iron is more easily absorbed by the body. 

Meat, seafood, and poultry have both heme and non-heme iron. Plant foods and iron-fortified foods have non-heme iron. Non-heme iron is more easily absorbed if you consume it alongside foods that have vitamin C (like citrus fruits, tomatoes, and broccoli). 

Some animal sources with the highest amount of iron include: 

• Oysters: 8 mg in 3 oz

• Beef liver: 5 mg in 3 oz

• Canned sardines: 2 mg in 3 oz

• Chicken: 1 mg in 3 oz

Some of the best plant-based sources of iron include:

• Fortified whole wheat cereal: 18 mg in ¾ cup 

• Canned white beans: 8 mg in 1 cup

• Boiled spinach: 3 mg in ½ cup

• Tofu: 3 mg in ½ cup

Keep in mind that your body doesn’t absorb all the iron present in foods. In general, you absorb somewhere between 15% to 35% of the heme iron present in food sources and about 2% to 20% of the iron in non-heme food sources. And the absorption of iron-fortified foods varies based on the type of iron that’s used.

Best iron supplements during pregnancy

There are many types of over-the-counter (OTC) iron supplements available on the market. Examples include:

• Ferrous gluconate

• Ferrous fumarate 

• Ferrous sulfate 

• Ferrous bisglycinate

No iron supplement is necessarily better than the other. But you may prefer one product over another for various reasons. For example, ferrous bisglycinate has been found to have fewer side effects than ferrous fumarate. It can also raise iron levels as much as ferrous fumarate, but with a lower dose. This may be important because the side effects or iron supplements are known to be dose-related.

Other factors may also come into play. Maybe you want a liquid or chewable iron supplement. Or maybe you prefer a supplement that’s vegan or vegetarian. Affordability may also be a factor. If your healthcare provider recommends an iron supplement during pregnancy, talk to them about which one is best for you. 

Regardless of which supplement you choose, pay attention to the amount of “elemental iron” in the product. Elemental iron refers to the amount of actual iron in a supplement. It’s more important than total iron because elemental iron represents the amount of iron the body can absorb. It’s usually the smaller number on the iron product’s label. For example, a ferrous sulfate 325 mg tablet contains 65 mg of elemental iron. 

It’s important to note that intravenous iron may be needed in severe iron-deficiency anemia during pregnancy or in situations where a person cannot take or absorb iron by mouth. 

Is there such a thing as too much iron in pregnancy?

Yes. Don’t take extra iron in pregnancy without talking to your healthcare provider.

For pregnant women without low iron levels, the established maximum amount of iron you should get from food and supplements combined is 45 mg/day. Iron intake above this amount may have negative effects, including high blood pressure in the mother or affecting the growth of an unborn baby. 

Keep in mind that this maximum amount may not apply to pregnant women with iron-deficiency anemia. Your healthcare provider may recommend doses greater than 45 mg per day in this situation. For instance, the WHO recommends a dose of 120mg/day of iron in pregnant women diagnosed with iron-deficiency anemia. 

Always check with your health care provider before starting an iron supplement. If you have low iron, they can help you make sure you’re taking a safe dose.

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Written by:

Rachel Feaster, PharmD, BCOP, BCPS

Rachel Feaster has over 10 years of professional experience in ambulatory, inpatient, pharmacogenomics, and oncology care. She is board certified in oncology and pharmacotherapy.

Edited by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

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