An increase in calcium intake can reduce the risk of preeclampsia in pregnant women by as much as 56 per cent, a group of doctors from the Singapore General Hospital (SGH), a member of the SingHealth​ group, has foun​d.

This finding is significant as the number of older first-time mothers in Singapore, who may also be obese, is rising. Advanced age and weight can increase the risk of preeclampsia.

What is preeclampsia?

Preeclampsia occurs when a pregnant woman develops high blood pressure and protein is found in her urine after the 20th week of pregnancy. It is a serious condition that affects multiple organs and can threaten the lives of the mother and her foetus. The symptoms can be treated but the only “cure” for preeclampsia is delivery, which can be before term if the disease is serious. The mother’s blood pressure can be expected to return to normal within a few weeks of delivery.

Pregnancy-induced high blood pressure or gestational hypertension, without the presence of protein in the urine, can also develop in pregnant women who are older and overweight. Gestational hypertension, which usually goes away after delivery, can lead to premature delivery and very low-weight babies.

Preeclampsia affects about 4 per cent of pregnancies in Singapore, said Dr Tan Lay Kok, Senior Consultant, Department of Obstetrics and Gynaecology, SGH, who was involved in the study.

Dr Tan and his colleagues reviewed the results of seven trials conducted on pregnant women in various countries between 1991 and 2009. The trials investigated the effects of calcium intake on the risks of developing preeclampsia and gestational hypertension.

“We wanted to find out if there are simple things that patients and their doctors can do to reduce their risk of contracting either condition,” said Dr Tan.

Supplement had most significant effect on women with low calcium intake

The SGH study looked at two groups of women. One group comprised those with a low calcium intake, that is, below the recommended dietary allowance (RDA) of 1g per day.

The other group was made up of those whose calcium intake was more than the RDA of 1g per day.

The women took an additional daily calcium supplement of at least 1g per day. Dr Tan’s team discovered that the supplement had the most significant effect on the group of women with a low calcium intake.

Based on the SGH study, when a woman with a low daily calcium intake was given more than 1g of calcium per day during her pregnancy, her risk of getting preeclampsia was reduced by as much as 56 per cent.

However, said Dr Tan, the number of women studied was too small for them to pinpoint the optimal amount of calcium that pregnant women should take to reduce their risk of developing preeclampsia.

The challenge now lies in applying this finding to clinical practice. “In Singapore, women don’t seem to take enough calcium. If their calcium intake is not adequate, doctors can encourage pregnant women to take more calcium, and this may help reduce their risk of getting preeclampsia,” said Dr Tan.

He added that he would give pregnant women, especially those at high risk of developing preeclampsia, a daily 1g calcium supplement. As long as the women don’t take more than the recommended dosage, the extra calcium will not pose any harm.

Other health risks faced by pregnant women

Gestational diabetes

This is high blood sugar (diabetes) that develops during pregnancy, usually late pregnancy. If gestational diabetes is not detected or managed effectively, the baby may be born premature. The delivery, too, may be difficult and more dangerous as the baby may be bigger than normal.

The baby also runs the risk of developing low blood glucose (hypoglycaemia) after birth and a higher chance of dying before or soon after birth. One of the best ways to maintain the mother’s blood glucose level within a target range is to follow a healthy diet and exercise.

Deep-vein thrombosis (DVT)

This is a serious condition involving the formation of blood clots in a vein deep inside a part of the body, often in the lower leg and thigh.

It can be fatal if the clot travels to the lungs. Pregnant women are more likely to suffer from DVT than non -pregnant women of the same age. A clot can form at any stage of pregnancy and up to six weeks after the birth. The treatment of DVT during pregnancy usually involves the injection of an anticoagulant.

Ref: S13