Study results suggest that taking calcium supplements during pregnancy may help protect against pregnancy-associated high blood pressure (hypertension) and pre-eclampsia.

If left untreated, hypertension and pre-eclampsia during pregnancy can lead to potentially life-threatening medical problems for mothers and babies. Indeed, according to the American College of Obstetricians and Gynecologists, pregnancy-associated hypertension is responsible for around 18% of maternal deaths in the USA alone, while pre-eclampsia, which affects an estimated 2% to 3% of first-time mothers, can lead to seizures and other complications.

For their study, Dr G Hofmeyr, from East London Hospital Complex in South Africa, and colleagues reviewed the results of 12 trials, involving more than 4000 women, which examined the effects of calcium supplementation in pregnancy.

Analysis of the findings revealed that women from communities with low dietary calcium intake could significantly reduce their risk of hypertension and pre-eclampsia by taking at least 1.5 g of calcium each day during the second half of pregnancy.

Although calcium supplementation did not reduce the risk of pre-eclampsia in women from communities with an adequate dietary intake of calcium, it was associated with 10% reduced risk of pregnancy-associated hypertension.

Furthermore, the researchers found that taking calcium supplements during pregnancy did not result in any adverse effects for mother or child.

"Calcium supplementation appears to reduce the risk of high blood pressure in pregnancy, particularly for women at high risk of gestational hypertension and in communities with low dietary calcium intake," conclude Dr Hofmeyr and team.

However, they add that further research is needed to identify the optimum calcium dose needed to prevent such pregnancy complications.

The review is published in the latest edition of The Cochrane Library.