I would have it be a permanent change that happens in the blink of an eye. No reason, no explanation, just an instantaneous shift in reality followed the 'thunk' as millions of woman fall to the ground limbless. I would like worldwide confusion, horror, and misery for an initial reaction, followed by quiet acceptance down the line as it becomes apparent things will never go back to the way they were before and females as we know them are replaced in the human consciousness by the helpless creatures they exist as in this post-catastrophic world.
No prosthetics for women either. None of them would have stumps, being just smooth limbless torsos, so mechanical ones wouldn't work and for some inexplicable reason, electric and other powered ones destroy themselves when placed on women, almost like they are emitting EMP waves from their bodies that deny any limb replacement from being attached.