This sheet is 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. Calcium carbonate has been used as an antacid to help symptoms of heartburn, acid indigestion, or 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 for calcium (elemental calcium). For people who are pregnant and over the age of 18 years, the RDA is 1,000 mg a day. For people who are pregnant and are ages 14 to 18 years old, the RDA of calcium is 1,300 mg a day. People can reach their RDA of calcium by eating foods with calcium in addition to calcium found in supplements and vitamins. If you have a medical condition that could affect your calcium levels, talk with your healthcare providers about the amount of calcium you need. Be sure to discuss all your exposures, including medications and over-the-counter supplements, with your healthcare providers.
I take calcium carbonate. Can it make it harder for me to become pregnant?
Taking calcium carbonate at recommended levels is not expected to make it harder to become pregnant.
Does taking calcium carbonate increase the chance for miscarriage?
Miscarriage can occur in any pregnancy. Based on the studies reviewed, taking calcium carbonate at recommended levels is not expected to increase the chance for 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. Based on studies reviewed, taking calcium carbonate at recommended levels is not expected to increase the chance for birth defects above the background risk.
Could taking calcium carbonate increase the chance of other pregnancy related problems?
When taken as directed, 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 higher than recommended levels of calcium carbonate?
The use of calcium carbonate in more than the recommended amount might cause low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth). In addition, taking more calcium carbonate than recommended has been associated with milk-alkali syndrome. Milk-alkali syndrome is caused by high levels of calcium in the blood. This might lead to the breakdown of calcium in other body tissues and could cause kidney failure. There have been a few case reports of newborns with seizures when high doses of calcium carbonate were used near the end of pregnancy. Case reports have limited value as they may not include important information that could also explain the outcomes reported
Breastfeeding while taking calcium carbonate:
There are Recommended Daily Allowance (RDA) guidelines for calcium (elemental calcium). For people who are breastfeeding and are over the age of 18 years, the RDA is 1,000 mg. For people who are pregnant and are ages 14 to 18 years old, the RDA of calcium is 1,300 mg.
Calcium is found in breastmilk. When calcium carbonate is taken 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 male takes calcium carbonate, could it affect fertility (ability to get partner pregnant) or increase the chance of birth defects?
Studies have not been done to see if calcium carbonate could affect male fertility 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.