Two new studies from the UK and Norway have found further evidence to suggest pre-eclampsia and cardiovascular diseases have some common roots.
The studies are published in the British Medical Journal (BMJ). One study is by David Williams, Consultant Obstetric Physician at the Institute for Women’s Health, Elizabeth Garrett Anderson Obstetric Hospital, University College London, UK, and colleagues and the other is by Elisabeth Balstad Magnussen, Research Fellow at the Department of Public Health, Faculty of Medicine, Trondheim, Norway and colleagues.
In the first study, researchers showed that pregnant women who have pre-eclampsia have four times the risk of heart disease later in life.
In the second study, researchers found that women who have cardiovascular risk factors years before they get pregnant are more likely to get pre-eclampsia while pregnant.
Pre-eclampsia is also known as pregnancy-induced hypertension. It occurs when blood pressure becomes abnormally high during pregnancy, together with high levels of protein in the urine or other unusual symptoms. It occurs in about 5 per cent of all first time pregnancies and can be harmful to both the mother and the unborn child.
The first study reviewed 25 earlier studies covering over 3 million women and worked out what the future heart disease related health risks might be for women who had pre-eclampsia during pregnancy.
The results showed a slight raise in overall rate of death for women who had had pre-eclampsia.
Women who had a history of the condition had four times the risk of increased blood pressure and two times the risk of fatal and non-fatal ischaemic heart disease, stroke, and blood clots (venous thromboembolism) later in life.
There was no increase in risk of any cancer which suggested the link between pre-eclampsia and cardiovascular disease was direct and particular.
The researchers said that women aged between 50 and 59 had a heart disease risk factor of 8 per cent without and 17 per cent with, a history of pre-eclampsia.
This risk went up to 14 per cent without, and 30 per cent with, a history of pre-eclampsia for women aged 60 to 69. These figures assume pre-eclampsia is not linked to other risk factors, said the authors.
They concluded that:
“The mechanism underlying this association remains to be defined, but whatever its nature, a history of pre-eclampsia should be considered when evaluating risk of cardiovascular disease in middle aged women.”
They suggested it might be advisable to offer women who have had pre-eclampsia preventative therapies at an earlier age than usual.
The second study analysed records on 3,494 women, of whom 133 (3.8 per cent) had pre-eclampsia during pregnancy. The researchers analysed the records to find out whether cardiovascular risk factors taken into account before pregnancy could be used to predict the likelihood of pre-eclampsia during pregnancy.
The data covered a range of cardiovascular risk markers, such as blood pressure, cholesterol levels, blood sugar levels, weight, and body mass index, taken before pregnancy.
After taking into account potential confounding factors such as smoking status and certain demographic variables, the researchers calculated that the chances of getting pre-eclampsia were 7 times higher for women who had high blood pressure, cholesterol and blood sugar before pregnancy compared to women who had normal levels of these risk factors.
They also found that a history of ischaemic heart disease, high blood pressure, or diabetes was linked with two times the risk in each case. Being overweight or obese also carried a higher risk compared to women who were not.
Interestingly women who used oral contraceptives just before becoming pregnant had half the risk of pre-eclampsia in pregnancy compared to women who had never used them or stopped using them some time earlier.
The reseachers wrote that their findings showed that risk factors for cardiovascular disease that were around years before a woman gets pregnant significantly increase the risk that she will get pre-eclampsia while pregnant. This suggests that pre-eclampsia and cardiovascular diseases may have common causes.
It is also possible they said, that pre-eclampsia itself has a direct causal effect on cardiovascular risk.
An editorial in the same issue of the journal says that while more research is needed to establish whether women with a history of pre-eclampsia should have more aggressive or earlier treatment for cardiovascular risks, the messages about reducing such risks and preventing cardiovascular diseases apply equally to all women.
“Pre-eclampsia and risk of cardiovascular disease and cancer in later life: systematic review and meta-analysis.”
Leanne Bellamy, Juan-Pablo Casas, Aroon D Hingorani, David J Williams.
BMJ Published online 1 November 2007.
doi:10.1136/bmj.39335.385301.BE
“Prepregnancy cardiovascular risk factors as predictors of pre-eclampsia: population based cohort study.”
Elisabeth Balstad Magnussen, Lars Johan Vatten, Tom Ivar Lund-Nilsen, Kjell Åsmund Salvesen, George Davey Smith, Pål Richard Romundstad.
BMJ Published online 1 November 2007.
doi:10.1136/bmj.39366.416817.BE
Written by: Catharine Paddock