Dietary supplements could prevent a dangerous complication of pregnancy, research has suggested.
Up to one in ten pregnancies is affected by pre-eclampsia, with symptoms including high blood pressure, headaches, blurred vision and swelling.
The exact cause is unknown, but it is thought to be linked to problems with blood vessels in the placenta.
In the latest study, published in the British Medical Journal, experts assessed the impact on the risk of pre-eclampsia of a supplement containing an amino acid and antioxidant vitamins.
Some experts have said the condition is linked to a deficiency in L-arginine, an amino acid that helps to maintain a healthy blood flow. Others think antioxidants could help protect women.
More than 600 pregnant women at high risk of pre- eclampsia, including many who had a previous pregnancy complicated by the condition, were given daily food bars during the research.
There appeared to be a much-reduced risk of pre-eclampsia among those who were given L-arginine and antioxidants.