Spider veins are not needed for your circulation. They are actually unnecessary detours that can safely be destroyed. Numerous vessels can be treated in one session. In general, spider vein treatment is not covered by insurance. Being overweight and child bearing tend to worsen spider veins.
Spider veins are more common in women and become more numerous with age.
The reason these veins stretch is not known. Trauma to an area can cause spider veins to form. There is no reliable means of prevention. Spider veins are harmless. The only reason for treatment is strictly cosmetic.