During pregnancy, not only are your hormones raging, you also have an increased volume of blood plus the additional weight that pregnancy brings that all lead to increased pressure on your veins. This increased pressure can force them to the surface of the skin to become very visible.
Spider veins (or telangiectasia) commonly form during pregnancy due to hormone changes and the added stress on your veins. Spider veins are a form of vascular lesion which are malformations of veins, capillaries, lymphatic vessels and arteries. They appear as red, purple or bluish lines or clusters of lines on the legs, nose, face and neck and they can make you feel self-conscious.