Trends in Venous Thromboembolism among Pregnancy Hospitalizations—U.S, 1994–2008

Background: Venous thromboembolism (VTE) during pregnancy is associated with acute and chronic effects and is a leading cause of maternal morbidity and mortality in the U.S. While some studies have evaluated trends in pregnancy-related VTE in the past, recent national temporal trends have not been documented. This study characterizes trends in pregnancy-related VTE during 1994-2008 and evaluates the prevalence of co-morbid conditions.

Methods: We included pregnancy-related hospitalizations with VTE in women 15-44 from the Nationwide Inpatient Sample (1994-2008) using ICD-9 diagnostic, procedure and diagnostic-related group codes. Chi square tests were used to determine differences in prevalence of VTE hospitalizations and multivariable logistic-regression analysis, to estimate the risk of VTE occurring with co-morbid conditions. Antenatal, delivery, and postpartum hospitalizations were evaluated separately and all estimates were weighted to account for the complex sample design.

Results: From 1994–2008, there was a 22% increase in the rate of antenatal hospitalizations with VTE (from 1.89 to 2.21 per 1,000 deliveries) and a 50% increase in post partum hospitalizations with VTE (from 0.41 to 0.62 per 1,000 deliveries)The prevalence of co-morbidities in women with VTE— obesity, increased from 3.0%–7.4% among antenatal hospitalizations. Diabetes increased from 6.6%–8.8%; chronic heart disease from 5.6% –8.6% and hypertensive disorders from 9.6% –12.7% among delivery hospitalizations.

Conclusions: The occurrence of pregnancy associated VTE have increased from 1994-2008. The observed trend may be due to concomitant increases in co-morbid conditions; heart disease, hypertensive disorders, and diabetes. These findings are important for design, planning and implementation of programs which focus on reduction of maternal morbidity and mortality.