Babies draw on their mother’s calcium during pregnancy (especially in the third trimester) and breastfeeding. It’s recommended that women who are pregnant or breastfeeding get at least 1,000mg of calcium each day, preferably from their diet.
However, if you’re unable to get the recommended amount of calcium in your diet, your doctor, midwife or obstetrician may recommend a calcium supplement. A calcium supplement may also be recommended for pregnant women who are at risk of pre-eclampsia, a pregnancy-related complication due to high blood pressure and protein in urine. This is usually started from 20 weeks’ gestation in the second trimester.
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What dose of calcium should I take if I’m pregnant or breastfeeding?
When choosing a supplement, it’s important to look specifically at the ‘elemental calcium’ which is the actual amount of calcium in the supplement available for your body to absorb. The elemental calcium amount is always listed on the product label.
Usually 500-600mg elemental calcium each day is enough to boost calcium levels to the recommended daily amount. The dose you need depends on how much calcium you get from your diet and your medical status.
What are the different types of calcium supplements?
Calcium supplements come in many different forms and brands. They can be purchased without a prescription at pharmacies, supermarkets and health food stores.
There are two types of calcium supplements available in Australian pharmacies: calcium carbonate and calcium citrate. There are other types in some pharmacies and health food stores.
Caltrate (calcium carbonate) and Citracal (calcium citrate) are the most popular brands, compared side-by-side in the table below.
Calcium carbonate contains more elemental calcium but does need to be taken with food to be absorbed. Calcium citrate contains less elemental calcium so can be costly if you are taking 500mg (2 tablets) or more each day.
Most people don’t get any side effects from calcium supplements. Calcium carbonate is more likely than calcium citrate to cause constipation and bloating. Too much calcium supplements can cause constipation, kidney stones and other health issues, so make sure to check with a health professional what dose is right for you.
All calcium supplements are quite large in size, often they’re described as ‘horse tablets’. But they are available as effervescent or chewable tablets, or in liquid forms, if you have trouble swallowing large tablets. However, these forms are usually more expensive than standard tablets.
Many pregnancy multivitamins contain calcium too, but often the dose is low, usually about 50-100mg of elemental calcium.
I don’t currently take a calcium supplement but if recommended by a health professional, my preference would be calcium citrate for the convenience of being able to take it without food and to avoid the risk of constipation.
When is the best time to take a calcium supplement?
There are some reports that taking calcium supplements at night is best, but there isn’t enough research to conclude this.
Just be sure to space out your calcium intake throughout the day because the body absorbs about 500mg calcium at a time. If you’re going to have a meal containing a high amount of calcium foods then take your supplement at another time that day.
Also, Calcium supplements can interact with some prescription medications and supplements (e.g. iron) so you may need to avoid taking them at the same time, but separate them by a few hours or different mealtimes. Check with a doctor or pharmacist for specific advice.
WHO. Guideline: Calcium supplementation in pregnant women. Geneva, World Health Organization, 2013.