Varicose veins, sometimes called spider veins, also occur frequently during pregnancy. In addition to being uncomfortable, these large swollen veins can increase your risk for Deep Vein Thrombosis (DVT.) DVT can be a life-threatening condition exacerbated by poor circulation that causes a blood clot. Motif maternity compression socks help by reducing the size of the blood vessels in the legs, which boosts return blood flow to the heart, preventing it from collecting in the lower extremities.