The Importance of Calcium in Pregnancy

December 22, 2014

Pretty pregnant woman holding a bowl of salad while standingBy Dr Lisa Watson, ND

One of the most important nutrients for human health is calcium. Calcium is necessary for the maintenance of strong bones and teeth, for heart health and blood pressure, for your nervous system and for your muscles.

During pregnancy we focus on calcium both as a nutrient necessary for your baby’s development and for maintaining healthy bones across mom’s lifetime. If your calcium levels aren’t adequate during pregnancy your baby will take the calcium from your bones, possibly leading to osteoporosis later in life.

Functions of Calcium

Calcium is the most abundant mineral in the body! 99% of it is stored in the bones and teeth and is necessary for maintaining a strong bone matrix. But calcium does so much more than that!

Calcium helps to relax muscles – including the heart muscle. Deficiencies of calcium in pregnancy can lead to muscle cramping and increased blood pressure (gestational hypertension) which can lead to pre-eclampsia.

Calcium is also involved in the formation of blood clots. This is of particular importance during labour and delivery when changes in blood clotting can lead to increased blood loss.

Calcium in Pregnancy

Canada guidelines suggest the daily recommended intake for elemental calcium during pregnancy is 1000mg for women over 18 and 1300mg for women under 18 (this reflects the increased need for calcium during adolesence). This amount is the same as is recommended for non-pregnant women because the absorption of calcium goes up during pregnancy!

The upper tolerable limit for calcium during pregnancy is 2500mg. There is an upper tolerable limit established because excess levels of calcium can decrease the absorption of iron and zinc (two very important minerals during pregnancy), lead to constipation and potentially increase the risk of kidney stones.

Should I Supplement Calcium During Pregnancy?

The importance of calcium in pregnancy can not be underestimated. However, supplements are not always necessary to meet your calcium needs.

The World Health Organization suggests that women at risk for gestational hypertension (high blood pressure in pregnancy) should take calcium supplements to prevent the development of pre-eclampsia. Women with one or more of the following risk factors may be at increased risk for gestational hypertension:

  • Obesity
  • previous pre-eclampsia
  • diabetes
  • chronic high blood pressure
  • kidney disease
  • autoimmune disease
  • first pregnancy
  • advanced maternal age
  • adolescent pregnancy
  • conditions associated with large placenta (twin pregnancy)

For the majority of pregnant women close attention to the diet is all that is required to get enough calcium during pregnancy. Many prenatal vitamins also contain a small amount of calcium in order to ensure women are reaching their recommended daily intake of calcium.

QUOTE: In populations where consumption of calcium on average meets the recommended dietary calcium intake, either through calcium-rich foods or fortified staple foods, calcium supplementation is not encouraged as it may not improve the outcomes related to pre-eclampsia and hypertensive disorders of pregnancy but might increase the risk of adverse effects. – World Health Organization


Dietary Sources of Calcium

The best thing about calcium is how abundant it is in our food supply! So many foods contain calcium – fruits, vegetables, nuts, seeds, grains and dairy products. Diets that eliminate dairy do NOT eliminate calcium!

Below are some phenomenal food sources of calcium.

Food Calcium content (mg)
Tofu (4 ounces) 774
Sesame seeds (1/4 cup) 351
Sardines (3 ounces) 347
Ricotta cheese (1/2 cup) 337
Orange juice (calcium fortified – 1 cup) 300
Yogurt (1 cup) 296
Collard greens (1 cup) 268
Spinach (1 cup) 245
Cheese (1 ounce) 204
Turnip greens (1 cup) 197
Mustard greens (1 cup) 165
Beet greens (1 cup) 164
Bok choy (1 cup) 158
Cow’s milk (1 cup) 138
Swiss chard (1 cup) 101
Kale (1 cup) 94
Almonds (1 ounce) 75
Cabbage (1 cup) 63
Broccoli (1 cup) 62
Brussels sprouts (1 cup) 56
Green beans (1 cup) 55
Cinnamon (2 tsp) 52
Oranges (1 medium) 52
Summer squash (1 cup) 48
Fennel (1 cup) 43
Asparagus (1 cup) 41
Celery (1 cup) 40
Leeks (1 cup) 31


Additionally, supplementing with a vitamin D supplement can increase the absorption of calcium and is recommended for all pregnant Canadians during the winter months.

If you are unsure you are meeting your calcium needs during pregnancy, consult with a Naturopathic Doctor who can guide you and help optimize your diet, your health, and the health of your baby.


Lassi et al. Essential pre-pregnancy and pregnancy interventions for improved maternal, newborn and child health. Repro Health2014;11 (Supp):S2

O’Brien et al. Serum 1,25-dihydroxyvitamin D and calcium intake affect rates of bone calcium deposition during pregnancy and the early postpartum period. Am J Clin Nutr 2012;96:64-72.

WHO. Guideline: Calcium supplementation in pregnant women. Geneva, World Health Organization, 2013.
Health Canada. Vitamin D and Calcium: Updated dietary reference intakes. 2012. Available online at:



LwatsonDr. Lisa Watson delivers health care that supports balanced and attainable health at all ages and stages of life. Of primary importance is health care that nurtures the body, mind, spirit, family and community.  As a Naturopathic Doctor and mother, Lisa believes that health care and a healthy lifestyle are intrinsically linked and that each serves to support the other. Dr. Watson practices at the Integrative Health Institute in Downtown Toronto.
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One Response to “The Importance of Calcium in Pregnancy”

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