Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Multicenter Study
. 2013 Nov 7:347:f6099.
doi: 10.1136/bmj.f6099.

Risk of first venous thromboembolism in pregnant women in hospital: population based cohort study from England

Alyshah Abdul Sultan  1 , Joe West, Laila J Tata, Kate M Fleming, Catherine Nelson-Piercy, Matthew J Grainge
Affiliations
Multicenter Study

Risk of first venous thromboembolism in pregnant women in hospital: population based cohort study from England

Alyshah Abdul Sultan et al. BMJ. .

Abstract

Objective: To examine the potential for preventing venous thromboembolism during and after antepartum hospital admissions in pregnant women.

Design: Cohort study using linked primary (Clinical Practice Research Datalink) and secondary (Hospital Episode Statistics) care records.

Setting: Primary and secondary care centres, England.

Participants: 206,785 women aged 15-44 who had one or more pregnancies from 1997 up to 2010.

Main outcome measure: Risk of first venous thromboembolism in pregnant women admitted to hospital for one or more days for reasons other than delivery or venous thromboembolism. Risk was assessed by calculating the absolute rate of venous thromboembolism and comparing these rates with those observed during follow-up time not associated with hospital admission using a Poisson regression model to estimate incidence rate ratios.

Results: Admission to hospital in pregnancy was associated with an increased risk of venous thromboembolism (absolute rate 1752/100,000 person years; incidence rate ratio 17.5, 95% confidence interval 7.69 to 40.0) compared with time outside hospital. The rate of venous thromboembolism was also high during the 28 days after discharge (absolute rate 676; 6.27, 3.74 to 10.5). The rate during and after admission combined was highest in the third trimester (961; 5.57, 3.32 to 9.34) and in those aged ≥ 35 years (1756; 21.7, 9.62 to 49.0). While the absolute rate in the combined period was highest for those with three or more days in hospital (1511; 12.2, 6.65 to 22.7), there was also a fourfold increase (558; 4.05, 2.23 to 7.38) in the risk of venous thromboembolism for those admitted to hospital for less than three days.

Conclusion: The overall risk of first venous thromboembolism in pregnant women increased during admissions to hospital not related to delivery, and remained significantly higher in the 28 days after discharge. During these periods need for thromboprophylaxis should receive careful consideration.

PubMed Disclaimer

Conflict of interest statement

Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: CNP was co-developer of the currently available guidelines on VTE prophylaxis in pregnancy issued by the Royal College of Obstetricians and Gynaecologists (green top guideline 37a). CNP has also received honorariums for lectures from Leo Pharma and Sanofi Aventis (makers of tinzaparin and enoxaparin, low molecular weight heparins used in obstetric thromboprophylaxis) and has received payment from Leo Pharma for development of an educational “slide kit” about obstetric thromboprophylaxis.

Figures

None
Fig 1 Division of antepartum person time into “hospitalised time” and “time outside hospital”
None
Fig 2 Rate of venous thromboembolism per 100 000 person years by weeks after discharge during antepartum period: 12 events in weeks 1-2 after discharge, 7 events in weeks 3-4 after discharge, and 12 events in weeks 5-10 after discharge
See this image and copyright information in PMC

Comment in

References

    1. Saving Mothers’ Lives: Reviewing maternal deaths to make motherhood safer: 2006-2008. Br J Obetet Gynaecol 2011;118:1-203. - PubMed
    1. Drife J. Thromboembolism. Br Med Bull 2003;67:177-90. - PubMed
    1. Wik H, Jacobsen A, Sandvik L, Sandset P. Prevalence and predictors for post-thrombotic syndrome 3 to 16 years after pregnancy-related venous thrombosis: a population-based, cross-sectional, case-control study. J Thromb Haemost 2012;10:840-7. - PubMed
    1. Jacobsen AF, Skjeldestad FE, Sandset PM. Ante- and postnatal risk factors of venous thrombosis: a hospital-based case-control study. J Thromb Haemost 2008;6:905-12. - PubMed
    1. Knight M. Antenatal pulmonary embolism: risk factors, management and outcomes. Br J Obstet Gynaecol 2008;115:453-61. - PubMed

Publication types