"Held: 1. The physician appellants have standing to challenge the foregoing provisions of the Act with the exception of § 7, the constitutionality of which the Court declines to decide. Doe v. Bolton, 410 U. S. 179. P. 428 U. S. 62, and n. 2. 2. The definition of viability in § 2(2) does not conflict with the definition in Roe v. Wade, 410 U. S. 113, 410 U. S. 160, 410 U. S. 163, as the point at which the fetus is "potentially able to live outside the mother's womb, albeit with artificial aid," and is presumably capable of "meaningful life outside the mother's womb." Section 2(2) maintains the flexibility of the term "viability" recognized in Roe. It is not a proper legislative or judicial function to fix viability, which is essentially for the judgment of the responsible attending physician, at a specific point in the gestation period. Pp. 428 U. S. 63-65. 3. The consent provision in § 3(2) is not unconstitutional. The decision to abort is important and often stressful, and the awareness of the decision and its significance may be constitutionally assured by the State to the extent of requiring the woman's prior written consent. Pp. 428 U. S. 65-67. 4. The spousal consent provision in § 3(3), which does not comport with the standards enunciated in Roe v. Wade, supra, at 410 U. S. 164-165, is unconstitutional, since the State cannot "'delegate to a spouse a veto power which the [S]tate itself is absolutely and totally prohibited from exercising during the first trimester of pregnancy.'" Pp. 428 U. S. 67-72. 5. The State may not constitutionally impose a blanket parental consent requirement, such as § 3(4), as a condition for an unmarried minor's abortion during the first 12 weeks of her pregnancy for substantially the same reasons as in the case of the spousal consent provision, there being no significant state interests, whether to safeguard the family unit and parental authority or other vise, in conditioning an abortion on the consent of a parent with respect to the under-18-year-old pregnant minor. As stressed in Roe, "the abortion decision and its effectuation must be left to the medical judgment of the pregnant woman's attending physician." 410 U.S. at 410 U. S. 164. Pp. 428 U. S. 72-75."