"Roe announced a trimester approach Professor Archibald Cox has described as "read[ing] like a set of hospital rules and regulations. During the first trimester, "the abortion decision and its effectuation must be left to the medical judgment of the pregnant woman's attending physician"; in the next, roughly three-month stage, the state may, if it chooses, require other measures protective of the woman's health. 4 5 During the final months, "the stage subsequent to viability," the state also may concern itself with an emerging interest, the "potentiality of human life"; at that stage, 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.""