There are limited data on when postpartum readmissions for thromboembolism occur after delivery hospitalizations on a population basis in the United States.

We sought to characterize risk factors for and timing of postpartum venous thromboembolism readmission after delivery hospitalization discharge.

The Healthcare Cost and Utilization Project Nationwide Readmissions Database for calendar years 2013 and 2014 was used to perform a retrospective cohort study evaluating risk for readmission for venous thromboembolism within 60 days of discharge from a delivery hospitalization. Risks for deep vein thrombosis and pulmonary embolism were individually assessed. Obstetric, medical, demographic, and hospital factors associated with postpartum readmission for venous thromboembolism were analyzed. Risk was characterized as odds ratios with 95% confidence intervals. Both unadjusted and adjusted analyses were performed. Adjusted analyses included relevant obstetric, medical, demographic, and hospital factors within logistic regression models.

From Jan. 1 through Oct. 31 in 2013 and 2014, 6,269,641 delivery hospitalizations were included in the analysis. In all, 2975 cases of readmission for any venous thromboembolism were identified (4.7 per 10,000 delivery hospitalizations) including 1170 cases of deep vein thrombosis and 1805 cases of pulmonary embolism. In all, 69.6% of readmissions for any venous thromboembolism occurred within the first 20 days of discharge vs 22.3% and 8.0% at 21–40 and 41–60 days after discharge. Median times to readmission were 12.7, 14.0, and 11.7 days for venous thromboembolism, deep vein thrombosis, and pulmonary embolism, respectively. Women readmitted for any venous thromboembolism were more likely to have a history of venous thromboembolism (4.2% vs 0.3%, P < .01), to have had a cesarean delivery (54.4% vs 32.4%, P < .01), to have a thrombophilia (1.8% vs 0.4%, P < .01), to have had a longer delivery hospitalization of >3 days for vaginal delivery and >4 days for cesarean (18.0% vs 6.6%, P < .01), to have been diagnosed with gestational hypertension or preeclampsia (19.7% vs 8.2%, P < .01), and to have had postpartum hemorrhage with transfusion (2.6% vs 0.5%, P < .01). These factors retained significance in adjusted models. History of venous thromboembolism and hemorrhage with transfusion were associated with the largest odds of readmission (odds ratio, 9.5; 95% confidence interval, 6.6–13.6, and odds ratio, 3.6; 95% confidence interval, 2.4–5.5, respectively). Other factors associated with increased odds included thrombophilia (odds ratio, 2.0; 95% confidence interval, 1.2–3.5), cesarean delivery (odds ratio, 2.0; 95% confidence interval, 1.8–2.3), longer delivery hospitalization (odds ratio, 1.8; 95% confidence interval, 1.5–2.2), and preeclampsia or gestational hypertension (odds ratio, 2.0; 95% confidence interval, 1.6–2.4).

While the majority of events occurred within 20 days of discharge, risk factors other than thrombophilia and prior venous thromboembolism were generally associated with modestly increased odds of events, and only a small proportion of readmissions occurred among women with thrombophilia and prior events. Our data demonstrate both the challenging nature and urgent need for further research to determine which clinical practices and interventions may reduce risk for venous thromboembolism readmissions on a population basis.