Tissue valves can either wear out or become calcified and stiffen over time. However, they are better
valves for use in childbearing years, as I’ll soon explain.
Mechanical valves are much more durable, and can last up to a lifetime. However, they require lifelong anticoagulation with medications such as warfarin, so that blood clots don’t form on the valve. Warfarin can cause major birth defects for unborn fetuses, and thus becomes more problematic for use during childbearing.