This sheet is about exposure to calcium carbonate in pregnancy and while breastfeeding. This information is based on available published literature. It should not take the place of medical care and advice from your healthcare provider.
What is calcium carbonate?
Calcium carbonate is a dietary supplement that has been used as an antacid to help symptoms of heartburn, acid indigestion, and upset stomach. Some examples of over-the-counter antacids with calcium carbonate are Tums®, Rolaids®, Maalox®, and Mylanta®.
The supplement label should list both the calcium carbonate dose along with the actual calcium dose, which is often listed as ‘elemental calcium’. There are Recommended Daily Allowance (RDA) guidelines and upper limit amounts for calcium (elemental calcium). For people who are pregnant and/or breastfeeding and age 19 or older, the RDA is 1,000 mg a day, and the upper limit is 2,500 mg. For people who are pregnant and/or breastfeeding and are ages 14 to 18 years old, the RDA of calcium is 1,300 mg a day and the upper limit is 3,000 mg. People can reach their RDA of calcium from the foods and beverages they consume as well as the calcium found in supplements and vitamins. If you have a medical condition that might change your calcium levels, talk with your healthcare providers about the amount of calcium that is right for you.
I take calcium carbonate. Can it make it harder for me to get pregnant?
When used as directed and within the recommended amounts, taking calcium carbonate is not expected to make it harder to get pregnant.
Does taking calcium carbonate increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. When used as directed and within the recommended amounts, taking calcium carbonate is not expected to increase the chance of miscarriage.
Does taking calcium carbonate increase the chance of birth defects?
Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. When used as directed and within the recommended amounts, calcium carbonate is not expected to increase the chance of birth defects above the background risk.
Does taking calcium carbonate in pregnancy increase the chance of other pregnancy-related problems?
When used as directed and within the recommended amounts, taking calcium carbonate is not expected to increase the chance of other pregnancy-related problems such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth).
Does taking calcium carbonate in pregnancy affect future behavior or learning for the child?
Studies have not been done to see if calcium carbonate can cause behavior or learning issues for the child.
What if I take more than the recommended amounts of calcium carbonate?
The use of calcium carbonate in more than recommended amounts might increase the chance of low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth). There have been a few case reports of newborns with seizures when high doses of calcium carbonate were used near the end of pregnancy. Also, taking more calcium carbonate than recommended can cause milk-alkali syndrome, a condition in which there is a high level of calcium in the body (hypercalcemia) and could lead to kidney failure or inflammation of the pancreas in the person who is pregnant.
Breastfeeding while taking calcium carbonate:
Calcium is found in breastmilk. When used as directed and within the recommended amounts, calcium carbonate is unlikely to be harmful to a nursing baby. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a male takes calcium carbonate, could it affect fertility or increase the chance of birth defects?
Studies have not been done to see if calcium carbonate could affect male fertility (ability to get partner pregnant) or increase the chance of birth defects. In general, exposures that fathers or sperm donors 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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OTIS/MotherToBaby encourages inclusive and person-centered language. While our name still contains a reference to mothers, we are updating our resources with more inclusive terms. Use of the term mother or maternal refers to a person who is pregnant. Use of the term father or paternal refers to a person who contributes sperm.
