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Your Pregnancy Matters

Why women should ‘pump iron’ supplements during pregnancy

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Taking iron during pregnancy helps build up extra blood women need for delivery.

You’ve just found out you’re pregnant. Now you’re focused on “doing everything right,” like eating a healthy diet, getting exercise, and choosing the proper prenatal vitamins – including iron supplements.

Taking iron helps your body produce more blood. That’s a big deal for moms-to-be, because your total blood volume will double over the course of your pregnancy!

The average pregnant woman needs about 30 mg of elemental iron per day to meet the new demands of extra blood volume, the developing placenta, and growing fetus. Most combination prenatal vitamins contain this much iron, which is nearly double the amount a nonpregnant woman requires. However, you might need more than 30mg a day if you:

  • Have low iron (iron-deficiency anemia) at the start of your pregnancy
  • Are carrying twins or triplets
  • Took iron sporadically in early pregnancy
  • Started taking iron late in pregnancy

Approximately half of your iron intake will go toward the developing fetus and placenta. The other half will be used to increase the amount of blood in your circulatory system, which will help protect you during childbirth. In a typical vaginal delivery, you’ll lose approximately a pint (500mL) of blood; for a cesarean section, it’s closer to two pints (1,000mL). Having low blood volume can lead to complications during delivery and the postpartum period.

Though iron supplements sometimes get a bad rap due to moderate side effects like constipation, most pregnant women should take them. Use these recommendations to properly “pump iron” during your pregnancy.

"Taking iron helps your body produce more blood. That’s a big deal for moms-to-be, because your total blood volume will double over the course of your pregnancy!"

Robyn Horsager-Boehrer, M.D.

6 tips for proper iron supplementation

1. Know your numbers

Most women will start the pregnancy with a mid-to-upper 30s hematocrit level – the percent of red blood cells in the total blood volume. You might see another number related to your blood count listed in your prenatal lab work – the hemoglobin level. A normal volume is around 12mg/dL. 

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Generally, we define iron-deficiency anemia in pregnancy as a hematocrit level of 30% (or a hemoglobin level less than 10mg/dL) in the third trimester. But remember, pregnancy does weird things to the body. For example, your plasma levels will increase more than your red blood cells, which can skew your lab results.

Don’t be surprised if your lab report suggests your hemoglobin or hematocrit is too low – the standard guidelines are meant for non-pregnant adults. Most Ob/Gyn providers will repeat the test in the third trimester to make sure you’re not anemic when you deliver. The timing gives us a chance to do some last minute intensive iron supplementation if necessary.

2. Read supplement labels

The label on your prenatal vitamins should list the amount of elemental iron in each dose. Look for the word “ferrous,” which might appear as one of the following names for elemental iron:

  • Ferrous gluconate
  • Ferrous sulfate
  • Ferrous fumarate

It doesn’t matter what form of iron you take – all are effective. Generic and brand name iron supplements usually work equally well. I encourage women to try different formulations until they find one they tolerate. Remember, iron only works if you actually take it.

Taking too much iron is unlikely to harm you or your growing fetus. If you’re concerned talk with your doctor about optimizing your dosage. 

3. Handle one issue at a time     

Taking iron supplements can make morning sickness symptoms worse during the first trimester. If you’re struggling with nausea and vomiting, you can wait a few weeks for it to subside before you try taking iron again. We’d much rather have patients successfully manage morning sickness early on – there’s plenty of time for iron supplements to work in the second and third trimesters.

4. Keep things moving     

If iron worsens constipation, add iron-rich foods that also provide fiber to your diet, such as beans, spinach, and fortified whole-grain cereals. However, we don’t recommend relying on food alone to get the total iron you need in pregnancy. 

For persistent constipation, try a stool softener like docusate sodium. Some iron supplements come as a stool softener combination. Or consider increasing fiber in your diet or taking a fiber supplement.

5. Find a formulation that works     

If you have trouble swallowing pills, try a liquid or chewable iron supplement. Just check the label to know how much you have to take to meet the daily recommended target of 30mg of elemental iron. 

Your doctor might recommend an IV infusion to help improve these symptoms or even more importantly, to increase blood volume as delivery gets closer.

6. Pump postpartum iron

Don’t throw out those iron pills once the baby arrives! You will most likely need to take them for a few more weeks to replace blood lost during childbirth. This is especially important if you had excessive blood loss with your delivery.

Taking iron is one of the most important things you can do for your growing baby – and for your own health.

Need guidance with iron supplementation? 

Call 214-645-8300 or request an appointment online.

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