They can't.
There is Constitutional protection for the right to abortion, which was ruled in the landmark decision in Roe v. Wade (1974).
The Supreme Court recognized that the right to an abortion is a fundamental liberty protected by under Fourteenth Amendment of the Constitution. Since this case, the Court has repeatedly reaffirmed the Constitution's protection for this imperative liberty, which warrants each person the right to make personal decisions about childbearing and family. If we're talking rule of law, in which federal law is the highest law of all, it's unconstitutional, in my opinion, for these states to restrict access to safe abortions; and for these states to interject themselves into the lives of women who wish to have an abortion or have the choice to have an abortion - a personal decision of hers that she has the right to make.
I'm pro-choice for my body. And I will always be pro-choice for anyone else's body. Because it is their right.