Antiphospholipid syndrome (APS) is frequently associated with complications during pregnancy. Miscarriage and maternal thrombosis are the most common problems, but prematurity, intrauterine growth retardation, pregnancy-induced hypertensive disorders, and pulmonary hypertension can complicate pregnancy as well. The correct treatment of these women requires an accurate preconceptual counseling and a close collaboration between obstetricians and physicians. Doppler studies of the umbilical and uterine arteries play an important role in predicting APS-related complications during pregnancy.