Al Jonsen, a professor of ethics in medicine at the University of Washington School of Medicine, said the findings raise the question of whether the science of saving premature babies has perhaps reached "some sort of physiological lower limit."
The barrier to survival may no longer be simply the traditional problem of insufficiently developed lungs, he said. It may now be what Jonsen called "a complex of physiological under-development" and "the illness of not being finished."
Jonsen said the findings raise two related, but separate, ethical questions:
"Is it justifiable to continue research into salvaging babies at the lower end of the scale?" he wondered. "What about rescue efforts? Can we legitimately exclude the whole class of babies under a particular weight and gestational age from therapeutic rescue efforts?"
The study's authors suggested their findings would be useful in guiding health care providers and administrators in making medical policy decisions, and also in counseling parents with "unrealistic expectations" about the ability of medicine to keep alive an immature infant outside of the womb.