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Two essential nutrients for pregnancy 1260x542

Two essential nutrients in pregnancy

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Naturopath Stephanie Hamilton looks at why calcium and magnesium are two crucial minerals needed in pregnancy.

During the second trimester of pregnancy, the baby’s skeleton and tooth enamel form and calcium and magnesium are needed in higher amounts. The baby will take all it needs from its mum for a healthy skeleton to form, so it is important that the mother adequately meets the higher demands during this time.

If the pregnant woman is not getting enough of these minerals, she may suffer from deficiency signs; a common symptom is leg cramps. These can happen at any stage of pregnancy, but often occur in the second trimester. Some women first take magnesium when they start experiencing muscle cramps in pregnancy, but calcium is also important.


Major food sources

  • Legumes
  • Whole grains
  • Nuts
  • Seeds
  • Dark green leafy vegetables
  • Cocoa

What does magnesium do in the body?
Magnesium is essential for a wide range of biological reactions in the body including hundreds of enzyme pathways and biological processes. Magnesium is important for energy metabolism, nerve conduction, muscle activity, immune function, and DNA synthesis and degradation. Magnesium also plays a structural role in bone and aids bone formation. During pregnancy, the demand for magnesium increases.

Dose in pregnancy
350 mg/day is the recommended dietary intake (RDI) for pregnant women aged 19-30 years. The RDI for pregnant women aged 14-18 years is 400 mg/day and the RDI for pregnancy women aged 31-50 years is 360 mg/day.

What type of magnesium is best?
Magnesium phosphate is a quick acting and gentle form of magnesium indicated whenever there are muscle spasms. It is especially indicated when the condition is better for heat and pressure.


Major food sources

  • Dairy products
  • Fish bones, especially salmon and sardines
  • Broccoli
  • Dark green leafy vegetables
  • Clams 
  • Black strap molasses

What does calcium do in the body?
Calcium is an essential mineral required for the building and maintenance of bones and teeth. Calcium is also needed for the proper functioning of a large number of processes in the body including muscle contraction, nerve conduction, heart beat, hormone release, blood coagulation, energy production and maintenance of immune function. After 12 weeks of gestation, maternal calcium absorption and excretion doubles.

One of the first signs of a calcium deficiency is known as tetany, which is characterized by muscle cramps and numbness and tingling in the arms and legs. Calcium can help calm the nerves and help promote sleep if taken before bed. There is also research suggesting that calcium may have a protective effect against pre-eclampsia.

Dose in pregnancy
1000 mg - 1300 mg/day is the RDI.

What type of calcium is best?
Calcium phosphate is safe and effective and works well with magnesium phosphate. Calcium phosphate has been used during times of rapid growth such as in pregnancy.

If you are thinking about becoming pregnant, preconception care should include making sure any deficiencies in calcium and magnesium are rectified. This will ensure your bones and teeth stay strong, and help you to physically cope with the nutritional demands of pregnancy and lactation.

If you are already pregnant, taking a calcium and magnesium supplement may help to address frustrating pregnancy leg cramps...and will hopefully allow you to get a better night’s sleep.

References available on request

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Dear Linnsie, I can understand that you are concerned about this supplement however it is difficult for me to provide you with much information as Blackmores do not have a product with tricalcium phosphate and therefore we do not hold evidence for its use and safety. I think it is important to discuss your concerns with your pharmacist, GP or Ob/gyn. You may also like to contact the company that produces the product you were taking as they will hold evidence for efficacy and safety. Another source of reputable information is Mother Safe hotline. MotherSafe is a free telephone service for the women of NSW, based at the Royal Hospital for Women, Randwick, that provide a comprehensive counselling service for women and their healthcare providers concerned about exposures during pregnancy and breastfeeding including the use of medications. The number is ph: 9382 6539 (Sydney Metropolitan Area) or 1800 647 848 (Non-Metropolitan Area). Linnsie,I hope this information is useful, please contact Blackmores Naturopathic Advisory on 1800 803 760 if you would like to discuss this further. And a big congratulations on your pregnancy, thanks, Danielle (Blackmores Naturopath).
I am 8 weeks of pregnancy. I've been taking calcium supplement for 10days. I just found out that the calcium I am taking is listed as pregnancy risk category C. I am taking calcium (as tricalcium phosphate). I am really scared that if it did harm my baby.
Is really dangerous take tricalcium phosphate?
Anonymous 07 Jan 2015
Dear Jaan,
Blackmores Bio Calcium product is suitable to use during pregnancy, however, unfortunately it is no longer available.
Calcium along with many of the minerals, is needed in higher doses throughout pregnancy as well as breastfeeding. It is important for you to be aware of the amount needed in your diet. Calcium is found in all dairy foods, calcium enriched soy milk, calcium enriched rice milk, dried figs, almonds, tahini, sesame seeds, canned salmon, broccoli, egg yolk, molasses and sardines.
I would suggest that you to speak to your health care practitioner regarding additional calcium supplementation.
I wish you all the best of health.
Kind regards, Rebekah (a Blackmores naturopath)

Dear all,
Do you guys know that whether the Blackmore BIO Calcium Tablets is good to be used by pregnant lady?
Many thanks.

Best Regards,
Anonymous 08 Jan 2014