I am 41 been back on combined oral contraceptive pill after a 10 yr break. noticed getting thread veins on my legs is this related?

Entirely possible: It could be that your thread veins are due to taking the pill but it is also possible that it is a pure coincidence and that your thread veins were going to show up now anyway. If you want to do something about them, see a vein specialist.

Can be: 50% of women by the time they are 50 have vein disease and goes up every decade. Oral contraception can cause more veins and pregnancies even more. Try 5 healthy vein practices: exercise like walking and biking, calf muscle pumping, elevate your legs, wear compression stockings for prolonged sitting and standing, dorsiflexion of ankle, eat or take bioflavonoids:grapefruit, pineapple, reservatrol.