General Obstetrics and Gynecology: Obstetrics
Venous thromboembolism during pregnancy and the postpartum period: Incidence, risk factors, and mortality

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Objective

The purpose of this study was to estimate the incidence, risk factors, and mortality from pregnancy-related venous thromboembolism.

Study design

The Nationwide Inpatient Sample from the Healthcare Cost and Utilization Project of the Agency for Healthcare Research and Quality for the years 2000 to 2001 was queried for all pregnancy-related discharges with a diagnosis of venous thromboembolism.

Results

The rate of venous thromboembolism was 1.72 per 1000 deliveries with 1.1 deaths per 100,000. The risk of venous thromboembolism was 38% higher for women ages 35 and older and 64% higher for black women. Other significant risk factors included thrombophilia, lupus, heart disease, sickle cell disease, obesity, fluid and electrolyte imbalance, postpartum infection, and transfusion. The risk factor with the highest odds ratio, 51.8 (38.7-69.2) was thrombophilia.

Conclusion

The incidence of pregnancy-related venous thromboembolism was higher than generally quoted. Women ages 35 and older, black women, and women with certain medical conditions and obstetric complications appear to be at increased risk.

Section snippets

Material and methods

Data for this study were obtained from the Nationwide Inpatient Sample (NIS), from the Healthcare Cost and Utilization Project (HCUP) of the Agency for Healthcare Research and Quality (AHRQ). The NIS contains data from 5 to 8 million hospital stays from about 1000 US hospitals and is the largest all-payer inpatient care database in the US. The NIS is a 20% stratified sample of all discharges and allows for national estimates. Included in the sample are general hospitals and academic medical

Results

During the period from 2000 to 2001, there were 9,058,162 pregnancy admissions and 73,834 postpartum admissions. Among the pregnancy admissions, there were 8,330,927 deliveries. Of these, 6,400,956 (77%) were vaginal and 1,929,971 (23%) were cesarean. There were 3375 arterial thromboembolic events (2850 strokes and 525 myocardial infarctions) in addition to the 14,335 venous thromboembolic events. Therefore, venous thromboembolic events were 4 times more common than arterial events. Among the

Comment

We found a higher incidence of pregnancy-related venous thromboembolism, 1.72 per 1000 deliveries, than has been previously reported. While none of the reports are from the US, and none have included as many cases, the previously published figures for the incidence of pregnancy-related venous thromboembolism range from 0.71 to 1.25 per 1000 deliveries.9, 10, 11, 12, 13, 14

Data from the Nationwide Inpatient Sample are limited to information derived from discharge abstracts. Consequently,

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    This study was funded in part by a grant from the National Institutes of Health (5K12-HD043446-03).

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