Intrauterine devices are a good way of keeping the numbers down. Contraception for idiots.
As an alternative to outlawing single motherhood (excepting only widows, and the legally divorced)? Although I am for taking the babies away from baby-moms, or forcing those single moms to live in supervised impounds I think forcing any medical procedure on a person is unacceptable.
By healthy presumption based on human history, a single mom raising a child is a form of abuse, and ends up raising a child that is a danger and cost to all. Yes, some percentage turn out okay, or even great. But the great majority is bound for prison and also for poverty, just for being born to single moms.