Trends in venous thromboembolism among pregnancy-related hospitalizations, United States, 1994-2009

Objective: The purpose of this study was to evaluate national trends in the rate of pregnancy-related hospitalizations for venous thromboembolism (VTE) from 1994-2009 and to estimate the prevalence of comorbid conditions among these hospitalizations.

Study design: An estimated 64,413,973 pregnancy-related hospitalizations among women 15-44 years old were identified in the 1994-2009 Nationwide Inpatient Sample. Trends in VTE-associated pregnancy hospitalizations were evaluated with the use of variance-weighted least squares regression. Chi-square tests were used to assess changes in prevalence of demographics and comorbid conditions, and multivariable logistic regression was used to evaluate the likelihood of VTE during the study period after adjustment for comorbid conditions. Antepartum, delivery, and postpartum hospitalizations were evaluated separately and reported in 4-year increments.

Results: From 1994-2009, there was a 14% increase in the rate of overall VTE-associated pregnancy hospitalizations; antepartum and postpartum hospitalizations with VTE increased by 17% and 47%, respectively. Between 1994-1997 and 2006-2009, the prevalence of hypertension and obesity doubled among all VTE-associated pregnancy hospitalizations; significant increases in diabetes mellitus and heart disease were also noted. A temporal increase in the likelihood of a VTE diagnosis in pregnancy was observed for antepartum hospitalizations from 2006-2009 when compared with 1994-1997 (adjusted odds ratio, 1.62; 95% confidence interval, 1.48-1.78).

Conclusion: There has been an upward trend in VTE-associated pregnancy hospitalizations from 1994-2009 with concomitant increases in comorbid conditions. Clinicians should have a heightened awareness of the risk of VTE among pregnant women, particularly among those with comorbid conditions, and should have a low threshold for evaluation in women with symptoms or signs of VTE.