Spider veins can go away on their own, but it is not likely. During pregnancy, there is increased venous back pressure in your legs. Spider veins can form because of this venous hypertension. It is especially likely if you suffered from leg swelling. A vein specialist can evaluate your problem and ask specific questions to see if you need further studies or if spider vein treatment alone is likely to be successful. Sclerotherapy, or injection of an FDA-approved drug into the spider veins, works by causing the small veins to go into spasm, and injures the vein lining. The veins eventually get absorbed by your body. Please be aware that spider vein elimination is a process, and you will need 2-3 treatments on average to make them disappear.