Can u die in pregnancy if on clexane (;anticoagulation) if had dvt in past?

Always possible: Pregnancy is actually a high risk situation regardless of if you are on anticoagulation. Add that into the mix and there are even higher risks. I am sure your OB is comfortable with dealing with that added complication, otherwise, he will refer you to a different specialist.

Unlikely: If you had a dvt, obviously that's why your doctor recommended you be on enoxaparin. While pregnancy is a state of increased possible thrombosis, the medication does help to prevent them. Follow your doctors instructions, exercise with light walking as much as you can, you should be fine.