"Abortion and Brain Waves" by Gregg Easterbrook, in The New Republic (Jan. 31, 2000), 1220 19th St., N.W., Washington, D.C. 20036.

When the Supreme Court decided Roe v. Wade in 1973, medical knowledge about the fetus was surprisingly limited. But that has changed in recent years, and what researchers have learned, argues Easterbrook, a senior editor at the New Republic, has important implications that neither pro-life nor pro-choice absolutists are likely to welcome.

The pro-life view, of course, is that life begins when sperm meets egg, producing what scientists call a zygote. (Until 1869, however, the Catholic Church held that life began 40 days after conception.) But in the scientific perspective today, "what happens early in the womb looks increasingly like cold-hearted chemistry," Easterbrook says, "with the natural termination of potential life far more common than previously assumed." Only about half of all zygotes implant in the uterine wall and become embryos. "Of those embryos that do trigger pregnancy, only around 65 percent lead to live births, even with the best prenatal care. The rest are lost to natural miscarriage. All told, only about one-third of sperm-egg unions result in babies, even when abortion is not a factor."

It may be possible, writes Easterbrook, "that God ordains, for reasons we cannot know, that vast numbers of souls be created at conception and then naturally denied the chance to become babies. But science’s new understanding of the tenuous link between conception and birth makes a strong case that what happens early in pregnancy is not yet life in the constitutional sense."

At the same time, however, "it has become increasingly clear that by the third trimester many fetuses are able to live outside the mother, passing a basic test of personhood. Now research is beginning to show that by the beginning of the third trimester the fetus has sensations and brain activity and exhibits other signs of formed humanity." The legal and moral implications "are enormous," Easterbrook observes. "After all, society increasingly uses cessation of brain activity to define when life ends. Why not use the onset of brain activity to define when life begins?"

In Roe, the Supreme Court said states could prohibit abortion in the third trimester, except when necessary "to preserve the life or health of the mother." This standard was considered "largely theoretical," Easterbrook says, because doctors then generally could not perform safe late-term abortions. In later rulings, the high court brushed aside Roe’s third-trimester protections, opting instead for the vague standard of fetal "viability." That has made "almost any late-term abortion permissible," he notes. An estimated 750 late-term abortions occur each year--less than one percent of all abortions in the United States. Most abortions (89 percent) occur in the first trimester.

With the Supreme Court now preparing to make another abortion ruling, Easterbrook favors dropping the "hopelessly confusing" viability standard for "a bright line drawn at the start of the third trimester, when complex fetal brain activity begins." That would neither undermine Roe’s abortion rights (since no complex fetal brain activity occurs before then) nor "enter into law poignant but unprovable spiritual assumptions about the spark of life."