Intensive care medicine today is as close to the miraculous as most of us are likely to see in our lifetime. Nowhere is this magic more effectively practiced than in neonatal nurseries. Infants who are born prematurely at twenty-four weeks gestation and who weigh less than a pound can now be treated successfully. No other type of medicine has a more dramatic payoff, for the infants who survive can look forward to seventy or more years of life. But...