Risk factors for venous insufficiency are numerous but the main two causes are heredity and pregnancy. The risk of developing superficial venous insufficiency increases with each successive pregnancy.
This is related to the increase in the total blood volume in the veins and in the increased pelvic pressure caused by the gravid uterus. The third trimester is when most of the severe venous changes in the legs occur.
Check out Dr. Joseph Magnant’s video below as he explains further regarding risk factors and causes for Varicose & Spider Veins.