Unfortunately it is age and it is very likely all of us at some point in our lives will be subjected to them. Research suggests at least one in five women in their 20s will have a thread vein, a figure that rises to around half by the age of forty. Pregnancy can also speed up the process of developing these little red lines. Hormonal changes related to pregnancy and menopause promote their development. This is one of the reasons why women seem to get them over men. Family genetics also play a fundamental part in the problem. Other causes include too much sunbathing, exposure to wind, extreme temperatures, jobs that involve prolonged standing and medications, all of which can be factored in to why you may have them. Thread veins do not impose a health threat, but they can be a serious cosmetic problem.