According to Swiss Medical Weekly, women how have had two or more full term pregnancy's develop varicose veins. Some of the common problems during pregnancy are:
Family history of varicose veins.
A venous condition was present before pregnancy.
Not enough exercise during pregnancy.
Sitting or standing for long periods at a time.
Wearing compression socks during pregnancy prevents blood clots from pooling to the veins and reduces elevated heart rate in both the mother and child. Once you've tried your first pair, you will want to continue wearing them for years after.