"In Roe v. Wade, the Court recognized that the State has "important and legitimate" interests in protecting maternal health and in the potentiality of human life. 410 U.S. at 410 U. S. 162. During the second trimester, the State "may, if it chooses, regulate the abortion procedure in ways that are reasonably related to maternal health." Id. at 410 U. S. 164. After viability, when the State's interest in potential human life was held to become compelling, the State "may, if it chooses, regulate, and even proscribe, abortion except where it is necessary, in appropriate medical judgment, for the preservation of the life or health of the mother." Id. at 165."