This sheet talks about exposure to calcium carbonate in pregnancy and while breastfeeding. This information should not take the place of medical care and advice from your healthcare provider.

What is calcium carbonate?

Calcium carbonate is a dietary supplement used to increase calcium in your body. Calcium is important because it helps many body parts stay healthy, such as your bones, muscles, nerves, brain, and heart.

Calcium carbonate is also used as an antacid to relieve heartburn, acid indigestion, and upset stomach. Calcium carbonate comes in different forms, including pill, chewable tablet, capsule, and liquid. Some examples of over-the-counter antacids with calcium carbonate are Tums®, Rolaids®, Maalox®, and Mylanta®.

I take calcium carbonate. Can it make it harder for me to become pregnant?

Based on the available information, taking calcium carbonate is not expected to make it harder to become pregnant.

I just found out I am pregnant. Should I stop taking calcium carbonate?

Talk with your healthcare providers before making any changes to this supplement. When taken as directed, recommended doses of calcium carbonate have not been associated with any known risks during pregnancy.

Does taking calcium carbonate increase the chance for miscarriage?

Miscarriage can occur in any pregnancy. Based on the available information, taking calcium carbonate is not expected to increase the chance for miscarriage.

Does taking calcium carbonate increase the chance of birth defects?

In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect. This is called her background risk. Based on the available information, taking calcium carbonate is not expected to increase the chance for birth defects about the background risk.

Could taking calcium carbonate cause other pregnancy complications?

Based on the available information, when taken as directed, recommended doses of calcium carbonate are not expected to increase the chance of complications in the pregnancy.

Does taking calcium carbonate in pregnancy cause long-term problems in behavior or learning for the baby?

There are no studies on the possible long-term effects of calcium carbonate on behavior or learning for the baby.

What are the dangers of taking too much calcium carbonate?

The Recommended Dietary Allowance (RDA) of calcium for pregnant and breastfeeding women is 1,000 mg to 1,300 mg. The use of calcium carbonate in more than the recommended amount can lead to lower fetal weight and has been associated with milk-alkali syndrome. Milk-alkali syndrome is caused by increased levels of calcium in the blood. This might lead to the breakdown of calcium in other body tissues, and may cause kidney failure. There have been a few case reports of newborns with seizure, possibly due to high doses of calcium carbonate that the pregnant woman took at the end of her pregnancy. Be sure to discuss all your exposures, including medications and over-the-counter supplements, with your healthcare providers.

Can I breastfeeding while taking calcium carbonate?

Calcium is found in breast milk. When calcium carbonate is used at recommended doses, it is unlikely to be harmful to a nursing baby. Be sure to talk to your healthcare provider about all of your breastfeeding questions.

If a man takes calcium carbonate, could it affect his fertility (ability to get partner pregnant) or increase the chance of birth defects?

There are no studies looking at possible problems with male fertility or risks to a pregnancy when the father takes calcium carbonate. In general, exposures that fathers have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.

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