"We agree with the District Court, and conclude that the definition of viability in the Act does not conflict with what was said and held in Roe. In fact, we believe that, § 2(2), even when read in conjunction with § 5 (proscribing an abortion "not necessary to preserve the life or health of the mother . . . unless the attending physician first certifies with reasonable medical certainty that the fetus is not viable"), the constitutionality of which is not explicitly challenged here, reflects an attempt on the part of the Missouri General Assembly to comply with our observations and discussion in Roe relating to viability. Appellant Hall, in his deposition, had no particular difficulty with the statutory definition. [Footnote 3] As noted above, we recognized in Roe that viability was a matter of medical judgment, skill, and technical ability, and we preserved the flexibility of the term. Section 2(2) does the same. Indeed, one might argue, as the appellees do, that the presence of the statute's words "continued indefinitely" favor, rather than disfavor, the appellants, for, arguably, the point when life can be "continued indefinitely outside the womb" may well occur later in pregnancy than the point where the fetus is "potentially able to live outside the mother's womb." Roe v. Wade, 410 U.S. at 410 U. S. 160."