SAN DIEGO—For pregnant women, the risk of thrombosis after giving birth remains significantly elevated for 12 weeks after delivery, according to an analysis of data from 1.7 million women presented at the 2014 International Stroke Conference. This period of elevated risk is twice as long as was previously thought.
Hooman Kamel, MD, Assistant Professor of Neurology at Weill Cornell Medical College in New York City, and his associates analyzed data for 1,687,930 women admitted to nonfederal acute care hospitals or emergency departments in California for first-time labor and delivery between 2005 and 2010. Of these women, 1,015 (0.06%) had a thrombotic event within 24 weeks after delivery. These events included strokes (248), myocardial infarctions (47), and venous thromboemboli (720).
The chance of a clotting event was 11 times higher than normal during the first six weeks after delivery. The risk of a clotting event during the first six weeks also was twice the risk of such an event occurring seven to 12 weeks after delivery, said Dr. Kamel. Twenty-two clot-related strokes, heart attacks, or venous thromboembolisms occurred within the first six weeks postpartum for every 100,000 deliveries. Three such events occurred in the following six weeks postpartum for every 100,000 deliveries.
Between 13 and 18 weeks after delivery, women’s risk of a blood clot was 40% higher than their risk during the same period one year later. The difference was not statistically significant, however, said Dr. Kamel. Between 19 and 24 weeks after delivery, women’s risk of a blood clot was the same as it is among women who have never delivered a baby.
The study confirms that thrombosis after delivery is rare and suggests that clinicians should be alert to possible symptoms of stroke beyond the first six weeks postpartum. Especially in women who have other risk factors for thrombosis, awareness of continued elevated risk during weeks seven to 12 could lead to quicker treatment if a blood clot forms, said Dr. Kamel.
—Sherry Boschert