How are you going to run track while pregnant?
What if she doesn't want to take a "leave"? Let her keep the scholarship while she can't run? I think the standard should be whether you're actually able to perform the terms of the contract (which is what an athletic scholarship is), i.e., running. Apply it equally to males and females. If a male develops some condition that prevents him from running, take away the scholarship.
And this is relevant to an athletic scholarship how?