"In Wade, the Court recognized that the State has an "important and legitimate interest in protecting the potentiality of human life." 410 U.S. at 410 U. S. 162. That interest was found to exist throughout a pregnancy, "grow[ing] in substantiality as the woman approaches term." Id. at 410 U. S. 162-163. See also Beal v. Doe, 432 U.S. at 432 U. S. 445-446. Moreover, in Maher, the Court held that Connecticut's decision to fund the costs associated with childbirth but not those associated with nontherapeutic abortions was a rational means of advancing the legitimate state interest in protecting potential life by encouraging childbirth. 432 U.S. at 432 U. S. 478-479. See also Poelker v. Doe, 432 U. S. 519, 432 U. S. 520-521. It follows that the Hyde Amendment, by encouraging childbirth except in the most urgent circumstances, is rationally related to the legitimate governmental objective of protecting potential life. By subsidizing the medical expenses of indigent women who carry their pregnancies to term while not subsidizing the comparable expenses of women who undergo abortions (except those whose lives are threatened), [Footnote 27] Congress has established incentives that make childbirth a more attractive alternative than abortion for persons eligible for Medicaid. These incentives bear a direct relationship to the legitimate congressional interest in protecting potential life. Nor is it irrational that Congress has authorized federal reimbursement for medically necessary services generally, but not for certain medically necessary abortions. [Footnote 28] Abortion is inherently different from other medical procedures, because no other procedure involves the purposeful termination of a potential life."