Pre-eclampsia is a complication in pregnancy occurring in approximately eight percent of all pregnancies. It is characterised by elevated blood pressure and protein in the urine. It generally develops after 20 weeks of pregnancy.
Medical doctor and researcher Bjoern Egil Vikse from the Department of Medicine at University of Bergen (UiB) is the first author of an upcoming article in the March issue of the Journal of the American Society of Nephrology.
Vikse explains that there were two reasons for becoming involved in this work. The first was that a collegaue had previously found a strong correlation between pre-eclampsia and a later incidence of cardiovascular disease. The second is that UiB researchers have a unique research tool. They have access to two large databases: one is a birth registry; the other is a kidney biopsy registry. This enables them to use large, well-documented data pools in their work.
The Birth Registry provided Vikse with data from 1967 and the Kidney Biopsy Registry dates from 1988.
Vikse and his colleagues first compared data from the two registries to see if there was a correlation between the children of mothers who had experienced pre-eclampsia and incidence of kidney disease in these children. They found no correlation.
They then compared the two databases for a possible correlation between the incidence of pre-eclampsia and later incidence of kidney disease in the mothers and found an unexpectedly strong result.
-We were amazed that the correlation was so strong," says Vikse. The data showed that pre-eclampsia alone was responsible for the mothers having a 3.3% increased risk of developing kidney disease later. If, in addition, the child had a low birth weight, the risk increased to a 4.8% increased risk with low birth-weight and a dramatic17% increased risk with very low birth-weight.
Another unexpected finding was that the increased risk was not associated with any particular kidney disease: all kidney diseases had a similar increased risk.
"You would expect the risk increase to be linked to a particular disease," explains Vikse. "It was most unusual to find that this was not the case."
Vikse explains that the researchers will now try to characterise the correlation further as well as checking for correlations with other medical conditions such as kidney failure. Studies into the development of both pre-eclampsia and kidney disease are also needed to see if there are any similarities between the mechanisms by which both medical conditions develop.
According to Vikse, there are also more far-reaching consequences as well. This result suggests that information about having experienced a pregnancy with pre-eclampsia should be included in a woman's medical history record. Such women need to be followed up for the rest of their lives because of their increased risk of cardiovascular and kidney disease.