One of the risks of any surgery is deep vein thrombosis (leg vein clots) with dislodgement of a clot that goes to the lung as a pulmonary embolus. This can cut off the normal blood flow to the lungs and cause death. Although this problem is unusual, anything you can do to reduce it is always a good idea. Birth control pills increase this risk. Therefore, if possible, stopping the birth control pills for a month before and after surgery is ideal. You must, however, consider the risks of getting pregnant when you decide to do this. You should also tell your surgeon about the birth control pills so other prophylactic measures, such as leg compressive devices, can be used if they are not routine.