A 24-year-old woman appears at 8 weeks of pregnancy and reveals a history of pulmonary embolism 7 years ago during her first pregnancy She was treated with intravenous heparin followed by several months of oral warfarin (Coumadin) and has had no further evidence of thromboembolic disease for over 6 years. Which of the following statements about her current condition is true?

Patients with a history of thromboembolic disease in pregnancy are at high risk of developing it in subsequent pregnancies. Impedance plethysmography and Doppler ultrasonography are useful techniques even in pregnancy and should be done as baseline studies. Patients should be treated prophylactically with low-dose heparin therapy through the postpartum period as this is the time of highest risk of this disease.