Hospital Admission Significantly Increased VTE Risk in Pregnant Women


The risk of venous thromboembolism is increased more than 17-fold when a pregnant woman is hospitalized for reasons other than delivery, research shows.

Pregnant women admitted to the hospital for reasons other than delivery had a more than 17-fold increased risk of venous thromboembolism compared with time outside the hospital during their pregnancy, according to the results of a large cohort study conducted in England.

“In the light of our findings, pregnant hospitalized women should receive careful considerations in terms of venous thromboembolism risk assessment, especially those in their third trimester or aged >35 years,” said study author Alyshah Abdul Sultan, a doctorate student in the division of epidemiology and public health at the University of Nottingham, Nottingham, United Kingdom.

According to Sultan, venous thromboembolism, which complicates 1 to 2 pregnancies in every 1000, is one of the leading direct causes of maternal deaths in developed countries. Although previous research has shown that hospital admission increases the risk of venous thromboembolism about 100-fold and is responsible for more than 25,000 deaths each year in the United Kingdom, the magnitude of risk of venous thromboembolism during antepartum admission and after discharge is unknown.

To explore the issue further, Sultan and colleagues conducted a study of 206,785 women aged 15 to 44 years who had one or more pregnancies from 1997 to 2010. The researchers examined venous thromboembolism in women admitted to the hospital for 1 or more days for reasons other than delivery or venous thromboembolism. Eighteen percent of the women’s pregnancies included at least 1 admission to a hospital, with a higher rate of admissions occurring during the third trimester.

Results indicated that women admitted to the hospital during pregnancy had an increased risk of venous thromboembolism of 16.6 cases per 1000 person-years compared with time outside the hospital. This increased risk translated into a 17.5-fold increased risk.

The researchers also found that hospitalized pregnant women had an increased risk of venous thromboembolism in the time immediately after discharge as well. During the 28 days after discharge, there was an excess risk of 5.8 cases per 1000 person-years.

Excess risk of venous thromboembolism was highest in women who were in their third trimester and those aged 35 years or older. In addition, although women admitted for 3 or more days had the highest risk of venous thromboembolism, even a hospital stay of less than 3 days conferred a 4-fold increased risk.

Pertinent Points:
- Pregnant women admitted to the hospital had a significantly increased risk of venous thromboembolism.
- The risk for venous thromboembolism in this population is highest for women in their third trimester, those aged 35 years, and those in the hospital 3 or more days.


Sultan AA, West J, Tata LJ, et al. Risk of first venous thromboembolism in pregnant women in hospital: population based cohort study from England. BMJ. 2013;doi:10.1136/bmj.f6099.

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