The father can keep his swimmers to himself if he's really that worried.
Fathers have a natural right to protect the lives of their own children, whether you endorse that right or not.
What I'm proposing is, in the absence of explicit consent to be responsible for the kid (with marriage being considered explicit consent), the woman can retain total control AND total responsibility for what comes out of her body.
Within marriage, abortion without husband's consent would be considered to trigger dissolution of the marriage for cause, without alimony.