Women are being warned about a link between pregnancy disorder pre-eclampsia and heart disease, as new evidence emerged connecting the two.
Pre-eclampsia can be symptomless
Two studies were published in the British Medical Journal, with one suggesting they share a common origin.
The other by a London team found women who have pre-eclampsia were twice as likely to develop heart disease.
Women who have pre-eclampsia should take precautions to protect themselves from heart disease, experts said.
Pre-eclampsia is a serious condition where abnormally high blood pressure and other disturbances develop in the second half of pregnancy.
It affects about 5% of all first-time pregnancies and is dangerous for both mother and child.
Researchers from London's Institute for Women's Health analysed 25 studies involving over three million women to calculate the future health risks of women who have had a pregnancy affected by pre-eclampsia.
They found women with a history of pre-eclampsia were four times more likely to suffer from high blood pressure and twice as likely to develop heart disease, stroke, and blood clots in later life. However, there was only a small increase in mortality.
And they found no increase in risk of any cancer, suggesting a specific link between pre-eclampsia and cardiovascular disease.
The report said the reasons for this remain unclear.
Lead researcher David Williams said: "A history of pre-eclampsia should be considered in the evaluation of women's risk of cardiovascular disease."
And he added it could lead to women being eligible for preventative therapies at an earlier age.
In the second study of 3,494 women, by a team at the Norwegian University of Science and Technology, blood pressure, cholesterol and blood sugar levels, weight, and body mass index were recorded before pregnancy.
Some 133 of these women ended up with pre-eclampsia.
The study found the odds of the pregnancy complication was seven times greater in women with high pre-pregnant blood pressure, cholesterol and blood sugar levels compared to women with readings in the normal range.
The findings suggest that pre-eclampsia and cardiovascular diseases may share a common origin, the authors said.
British Heart Foundation cardiac care nurse Cathy Ross said: "The results make it clear that women who have had pre-eclampsia, need to be aware of their increased risk and take action to reduce it."
She added this included "stopping smoking, being physically active and reducing the salt content in your diet".