Pulmonary embolism (PE), deep venous thrombosis (DVT), and the combination were not rare in pediatric patients in the United States from 1979 to 2001. They were more frequent in infants 0 to 1 year of age and in teenagers 15 to 17 years of age than in children 2 to 14 years of age. Pregnancies doubled the rate of DVT in teenage girls.