Identify Risk Factors Early to Prevent Blood Clots after Giving Birth

Researchers have identified a group of risk factors to predict whether a woman will develop any kind of deadly blood clots after giving birth.

A team of investigators from the University of Nottingham looked at 400,000 pregnant women to compile a complete list of the factors that increase the risk of venous thromboembolism (VTE) during and after pregnancy. Obesity, conditions like inflammatory bowel disease (IBD), varicose veins, heart disease, and any history of bleeding after conceiving or during labor, premature birth, giving birth via C-section or stillbirth are some of the factors included in the list.

VTE is a blood clot that is formed in the deep veins of the leg. The clots bring redness, swelling and pain to the legs. The condition becomes life-threatening (pulmonary embolism) when the blood clot manages to reach the lung and interferes with the normal functioning of the lungs. According to National Health Service (NHS) U.K., pregnant women are 10 times more likely to develop venous thrombosis than others. Health experts recommend women to treat VTE during pregnancy by taking a blood thinning injection, heparin. Since enough data is not available to prove the safety of the injection, health practitioners normally recommend the drug only during emergency cases.

For the study, researchers collected data from different sources, including medical records from hospitals and doctors, between the years 1995 and 2009. Factors like maternal age, BMI, smoking habit, method of giving birth, status of the birth - premature or stillbirth - and complications during pregnancy like pre-eclampsia, diabetes and high blood pressure were taken into consideration. Apart from that, the role of medical conditions like heart disease, inflammatory bowel disease and varicose veins were also analyzed.

Except maternal history of blood pressure, all the other factors increased the risks of VTE after giving birth, with women who had stillbirth having greater risk than others.

"Preventing VTE in pregnancy remains a challenging topic for clinicians since there is still disagreement as to which clinical, lifestyle, and socio-demographic factors qualify women as high-risk, and data are lacking about the relative impact of those factors on their risk of VTE," author of the study Dr. Matthew Grainge said in a news release.

"Our results provide valuable information to help clinicians identify high-risk pregnant women and new mothers who may require some form of intervention to prevent future clots. The findings support the use of heparin to prevent blood clots in the postpartum period, when the actual risk of VTE is highest, clear risk factors have been identified, and duration of care would likely be limited to a few weeks (as compared to treating throughout the pregnancy)," added Dr. Grainge.

The study has been published in the journal Blood.