Two research papers published in British Medical Journal (BMJ) add further weight to the theory that cardiovascular diseases and pre-eclampsia may share common causes or mechanisms. Pre-eclampsia is a medical condition where hypertension arises in pregnancy, and which is dangerous for both mother and child.
One of the studies suggests that women who have had pre-eclampsia during pregnancy have a more than two fold higher risk of heart disease in later life. Whereas, the second study says that women with cardiovascular risk factors, present years before pregnancy, may be predisposed to pre-eclampsia.
The first study, conducted in London, was based on the analysis of 25 studied involving over 3 million women to calculate the future health risks of women who have had a pregnancy affected by pre-eclampsia. It showed that women a small increase in overall mortality among women who had had pre-eclampsia.
The study further showed that women with a history of pre-eclampsia also had an almost four fold increased risk of high blood pressure (hypertension), and a two fold increased risk of fatal and non-fatal ischaemic heart disease, stroke, and blood clots (venous thromboembolism) in later life.
It, however, did not find any increase in the risk of any cancer, suggesting a specific relationship between pre-eclampsia and cardiovascular disease.
Given that the risk of a cardiovascular event increases with age, the authors of the study noted that absolute risk at age 50-59 years would be around 8 per cent without and 17 per cent with a history of pre-eclampsia. At the age of 60-69 years, the risk would be 14 per cent without and around 30 per cent for a woman with a history of pre-eclampsia, they add.
The authors have suggested that a history of pre-eclampsia be considered when evaluating risk of cardiovascular disease in middle-aged women.
In the second study, conducted in Norway, the researchers examined whether cardiovascular risk factors assessed before conception predicted pre-eclampsia. Their analysis included 3,494 women.
Several cardiovascular risk markers, including blood pressure, cholesterol and blood sugar levels, weight, and body mass index, were recorded before pregnancy.
The study showed that the odds of pre-eclampsia were seven times higher in women with high pre-pregnancy blood pressure total cholesterol and blood sugar levels in comparison with their normal counterparts.
It also showed that a family history of high blood pressure, ischaemic heart disease, or diabetes was each associated with a doubling in risk, while overweight and obese women also had a higher risk compared to women of normal weight.
The study's results indicated that unfavourable cardiovascular risk factors that were present years before pregnancy were strong predictors of pre-eclampsia.
Based on their findings, the researchers came to the conclusion that pre-eclampsia and cardiovascular diseases might share a common origin.
The authors, however, did not rule out the possibility that the pre-eclamptic process itself might also contribute to subsequent cardiovascular risk.