Quick answer
NIH gives 1,000 mg of calcium a day in pregnancy for women 19 and older, 1,300 mg for teens, and an upper limit of 2,500 mg. A Cochrane review of 27 trials in 18,064 women found an unexpected increase in HELLP syndrome with high-dose calcium, 16 cases against 6, though the numbers were small.1,2
Key facts
- NIH gives 1,000 mg of calcium a day in pregnancy for women 19 and older and 1,300 mg for teens, from food and supplements together.1,3
- The upper limit is 2,500 mg a day for pregnant women 19 and older and 3,000 mg for teens.1,3
- In a Cochrane review, two trials of 12,901 women found more HELLP syndrome with high-dose calcium, at 16 cases against 6, with a risk ratio of 2.67 (1.05 to 6.82).2
- Calcium carbonate causes gas, bloating and constipation more often than calcium citrate, and carbonate is the form in many antacids.1,3
- NIH says professional organizations recommend calcium in pregnancy for women with low calcium intakes, and the dose is a matter for the care team.1
What NIH says about calcium in pregnancy
NIH gives the same amount of calcium for pregnancy as for other women aged 19 to 50, 1,000 mg a day, and 1,300 mg for teens, and keeps the upper limits the same too. It reports that several professional organizations recommend calcium supplements during pregnancy for women with low calcium intakes, and it says the evidence behind those recommendations has weaknesses.1,3
Children aged 9 to 18 need 1,300 mg a day, as do pregnant and breastfeeding teens. Pregnant and breastfeeding women aged 19 and older need 1,000 mg.1,3
The upper limit for calcium from food and supplements combined is 2,500 mg a day for adults aged 19 to 50 and 2,000 mg from age 51. For children aged 9 to 18 it is 3,000 mg.1,3
The body absorbs calcium best in amounts of 500 mg or less at a time. Someone taking 1,000 mg a day from supplements does better with two smaller doses than one large one.1,3
What did the Cochrane review say about harms?
The review covered 27 trials with 18,064 women. Most were designed to look at blood pressure disorders of pregnancy, and this page covers only what it reports on harms. The main one was unexpected: in two trials with 12,901 women, HELLP syndrome, a serious pregnancy complication, was more common in the calcium group, at 16 cases against 6, with a risk ratio of 2.67 (1.05 to 6.82). The review graded that evidence as high-quality, yet noted that the number of events was low.2
The authors reported no clear effect of calcium on admission to neonatal intensive care, on stillbirth or on infant death before discharge. They warned that several results needed careful reading because of the possibility of small-study effects or publication bias.2
What about calcium carbonate, citrate, antacids and calcium magnesium?
NIH says the two most common forms in supplements are calcium carbonate and calcium citrate. Calcium carbonate appears to cause gas, bloating and constipation more often, and symptoms can be eased by smaller doses spread through the day, taking it with meals or switching to a different form. Calcium citrate can be taken without food.1,3
Calcium carbonate antacids provide about 270 to 400 mg of calcium in each chewable tablet or soft chew, depending on strength.1
NIH says calcium carbonate antacids give about 270 to 400 mg of calcium per chewable tablet, so frequent antacid use adds to the daily total. The sources checked do not report on antacids or on combined calcium and magnesium products in pregnancy, which is not a finding either way.1
Who should ask a doctor about calcium in pregnancy
- Anyone pregnant who takes calcium supplements, antacids and a prenatal vitamin, who should ask their doctor or pharmacist to add up the calcium against the 2,500 mg upper limit.1,3
- Anyone pregnant who has had kidney stones or has kidney disease, or has been told they have high blood calcium or a parathyroid condition.1
- Anyone pregnant who takes levothyroxine, a quinolone or tetracycline antibiotic, a bisphosphonate, dolutegravir or lithium, since calcium interacts with each.1
- Anyone pregnant with high blood pressure or a history of pre-eclampsia, who should ask the care team before changing calcium on their own.1
Questions people ask
Is calcium carbonate safe during pregnancy?
NIH gives 1,000 mg of calcium a day in pregnancy and an upper limit of 2,500 mg from all sources. Carbonate causes gas, bloating and constipation more often than citrate. Ask your doctor.1,3
Is calcium citrate safe during pregnancy?
NIH says calcium citrate causes these digestive effects less often than carbonate and can be taken without food. The same 2,500 mg upper limit applies. Ask your doctor or pharmacist.1
Is a calcium antacid safe during pregnancy?
The sources checked do not address antacids in pregnancy, which is not a finding either way. NIH says antacid tablets give about 270 to 400 mg of calcium each, which counts toward the total. Ask your pharmacist.1
Is calcium magnesium safe during pregnancy?
The sources checked do not report on combined calcium and magnesium products in pregnancy. Ask your doctor or pharmacist to check each mineral against its upper limit.1
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Sources
- Office of Dietary Supplements, National Institutes of Health. Calcium: Fact Sheet for Health Professionals. Updated June 22, 2026. Opened 2026-10-07.
- Hofmeyr GJ, Lawrie TA, Atallah ÁN, Torloni MR. Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems. Cochrane Database Syst Rev. 2018;10:CD001059. A Cochrane systematic review of randomized trials. Opened 2026-10-11.
- Office of Dietary Supplements, National Institutes of Health. Calcium: Fact Sheet for Consumers. Updated September 14, 2023. Opened 2026-10-07.
This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.