While constitutional lawyers, ethicists and theologians — in descending order of importance in the abortion debate — have been arguing in the 46 years since the Supreme Court attempted to settle the debate, some technologists have been making a consequential contribution to it. They have developed machines that produce increasingly vivid sonograms of fetal development. This concreteness partially explains the intensification of the debate.
Six states have passed "heartbeat bills" to ban abortions after a fetal heartbeat is detectable, approximately six weeks after conception. Such bills are, indeed, unconstitutional given the court's Roe ukase that abortion cannot be restricted before a fetus is viable outside the womb — which means, presumably, before the fetus is a child.
But why should "viability" be the dispositive criterion? Viable means capable of surviving outside the womb, which no infant can do without constant help that others must give. Must. No infants are "viable" in that all are helpless, and the law requires that help be given by those responsible for the infant.