Health news - Calcium supplements can help reduce complications during pregnancy
17 March 2006 - written by Alexander Whitehead for Bupa's health information team
Women who take calcium supplements during pregnancy may be less at risk of suffering severe health complications, according to a study published in the American Journal of Obstetrics and Gynaecology this month.1
What did the study show?
Researchers working for the World Health Organisation found that calcium supplements reduced the risks of the more serious complications associated with the condition pre-eclampsia. Pre-eclampsia is the development of high blood pressure and protein in the urine during pregnancy.
The study found that taking a calcium supplement did not reduce the incidence of pre-eclampsia itself. However, it did significantly reduce the likelihood that a woman would develop dangerous complications, like eclampsia and severe gestational hypertension. The risk of mother or child dying during or after pregnancy was reduced - as was the risk of premature births among younger women.1
The study concluded that pregnant women should make sure that they have adequate levels of calcium in their diets, or consider taking a calcium supplement if they have a low dietary calcium.
How was the study carried out?
Over 8300 women were selected for the study. All had low dietary calcium, about half of that normally recommended for pregnancy. Participants came from parts of the world where low dietary calcium is common, including South Africa, India, Egypt, Vietnam and Argentina.
The women were randomly divided into two groups. Members of one group received a daily tablet containing 1.5g of a calcium supplement. Members of the other received a placebo ("dummy") pill. All the women took the tablets from before week 20 of their pregnancies through to birth.1
What is pre-eclampsia?
Pre-eclampsia occurs in five percent of pregnant women, and it is more common in first pregnancies. The cause is not known. Symptoms include high blood pressure, swollen hands and face, and abnormally high levels of protein in the urine.
Eclampsia is a rare and serious complication of pre-eclampsia. It can be life-threatening and is characterised by one or more seizures or fits. It can happen at any point during pregnancy, although it mostly occurs within the last three months or just after birth. At worst, it can lead to coma or death.2
How many pregnant women go on to develop eclampsia?
Around one in 100 women with pre-eclampsia go on to develop eclampsia. That means around one in every 2000 pregnant women in the UK. With prompt treatment, the condition is rarely fatal. Less than two in 100 cases result in the death of the mother, although 35 percent of sufferers develop major complications, such as eye or brain damage.3
What is gestational hypertension?
Gestational hypertension is abnormally high blood pressure brought on by pregnancy, but which disappears after birth. It affects five to 10 percent of all pregnancies and is more common among mothers who are pregnant with their first child. It is often an early form of pre-eclampsia - 40 percent of women who develop gestational hypertension before 34 weeks' gestation go on to develop pre-eclampsia.4
What are the symptoms of gestational hypertension?
Most women will not show symptoms, so regular urine and blood pressure checks are essential and routinely performed in hospital. An important feature of gestational hypertension is that, unlike pre-eclampsia, there is no protein in the urine.
What is the recommended daily level of calcium intake for children and adults?
The recommended daily intake of calcium is 700mg for adults. For infants aged one to three, the recommended figure is 350mg. That rises to 450mg for those aged three to six and 550mg for children aged seven to 10. For adolescents aged 11 to 18, higher levels are recommended due to increased skeletal growth - 800mg a day for females and 1000mg for males.5
Do pregnant women need to take more than 700mg a day?
The current advice is that pregnant women in the UK do not need to take more than 700mg a day, although an extra 550mg a day is recommended during breastfeeding.5
What foods contain high levels of calcium?
Food rich in calcium include milk, cheese and other dairy products (except butter), green leafy vegetables like broccoli and cabbage (but not spinach), soya beans, nuts and bread. Eating fish like sardines and pilchards (where you eat the bones as well) is also an excellent source of calcium.6
Why does taking calcium help?
Calcium is a nutrient and the most abundant mineral in the body. It helps to grow and maintain strong and healthy bones and teeth. It also helps maintain cell structure and is important for normal blood clotting, nerve signal transmission and heart and muscle action. A regular intake of calcium can also help guard against conditions like osteoporosis.
Do many women in the UK have low calcium in their diet?
A recent report has revealed that, on average, women in the UK take in 777mg of calcium every day from food sources - a figure above the recommended minimum intake of 700mg. Men take in 1007mg - again, well above the recommended minimum. However, women aged between 19 and 24 do not, on average, get enough calcium in their diet.7
Is it best to get calcium from food, drink or supplements?
Generally speaking, a well-balanced diet is the best way to ensure you absorb enough calcium. Calcium in dairy products is considered to be more "bio-available" (ie more easily absorbed by the body) than calcium from plant sources (eg broccoli). Milk an excellent source of calcium.
Are supplements useful for all pregnant women, even those who eat enough calcium-rich foods?
Pregnant women who are young and/or breastfeeding may need extra calcium, whether through additional food or supplements. Every person is different, so take medical advice.
Bupa information:
- Bupa factsheet: Pre-eclampsia
- Bupa factsheet: What happens during pregnancy
Further information:
- National Childbirth Trust
0808 808 7777
www.nctpregnancyandbabycare.com - British Nutrition Foundation
www.nutrition.org.uk - Action on Pre-eclampsia
020 8864 3271
www.apec.org.uk
References
- Villar J, Abdel-Aleem H, Merialdi M, Mathai M, Ali M, Zavalta N Buscemi N et al. World Health Organisation randomised trial of calcium supplementation among low calcium intake pregnant women. American Journal of Obstetrics and Gynaecology 2006; 194, 639-49.
- NHS Online Health Encyclopaedia: Pre-eclampsia.
www.nhsdirect.nhs.uk - Clinical Green Top Guidelines - Management of Eclampsia (10). Royal College of Obstetricians and Gynaecologists, 1999.
www.rcog.org.uk - Hypertension in Pregnancy.
www.patient.co.uk - Expert Report on Vitamins and Minerals, 2003.
www.food.gov.uk - Food Standards Agency - Calcium.
www.eatwell.gov.uk - The National Diet and Nutrition Survey: adults aged 19 to 64 years, 2003 (3).
www.food.gov.uk
All pages were accessed on 13 March 2006.
