PARENTS USED TO HAVE TO WAIT until babies were born to find out if they had tragic birth defects. Then came two breakthrough fetal tests: amniocentesis, which can identify abnormalities in the 15th week of pregnancy; and chorionic villus sampling, which can be performed as early as the tenth week. Neither procedure is without risk, however, and when either succeeds in pinpointing a genetic defect, it forces would-be parents to make a terrible choice: Do they raise a child who might have a serious congenital affliction? Or do they suffer the torment and pain that accompanies an abortion?
Now couples who...