Researchers identified all women who developed VTE for the first time during their pregnancy, including deep vein thrombosis (DVT), then extracted important key information about the mother from their medical records including their age, body mass index (BMI) and whether they smoked.
In addition, they considered other pregnancy-related factors such as how the baby was delivered, whether it was a stillbirth or premature birth and any associated complications including pre-eclampsia, diabetes and high blood pressure.
Co-existing medical factors including varicose veins, inflammatory bowel disease (IBD) and heart conditions such as heart disease were also taken into account.
They then used sophisticated data analysis methods to calculate the incident rate ratios to compare the risks of VTE to people without the specified risk factor.
They discovered that the risk of VTE during pregnancy was only marginally higher for women who were aged over 35 years old, had a BMI greater than 25 or who smoked. Medical complications such as pre-existing diabetes, varicose veins and IBD were all associated with greater risk, but not pre-existing high blood pressure.
The risks were much higher for new mothers. Postnatal women with a BMI greater than 30 were four times more likely to develop a VTE, while delivery by caesarean section, multiple previous births (three or more), bleeding in pregnancy and premature birth all doubled the chances of a women developing a VTE.
Perhaps most significantly, women who suffered a still birth were six times more likely to have a VTE.
Dr Grainge added: "Our results may have important implications for the way that preventative measures for VTE are delivered in healthcare settings in developed countries. We believe the strong association between stillbirths and premature births and VTE in particular is a finding of real importance which has received only limited atten
|Contact: Emma Thorne|
University of Nottingham