Before the 20th century, babies born prematurely did not present much of a medical or social issue. If the infant was mature enough to suckle, it had a chance to survive. If not, it died quickly.

The development of a rubber catheter feeding tube that enabled milk to be passed directly to the infant's stomach initiated an era of rapid progress in the care of sick infants. In the years that followed, incubators were developed and perfected, respiratory care improved and the use of high-concentration oxygen was introduced. These innovations revolutionized the possibilities in the treatment of "preemies" and opened the way for the foundation of a new specialty -- neonatology, the scientific care of the newborn.

"Born at Risk," by former Washington Post reporter B. D. Colen, takes a look at the state of that specialty today. Using an engaging anecdotal format, Colen takes the reader through a day in the life of Dr. Jim Hannan, the fictionalized chief of neonatology at "Metropolitan Lying-In," the disguised name of a Washington hospital where the events in the book actually took place. The story moves nicely, covering quantities of medical and ethical ground rapidly. Colen has mastered the scientific concepts and jargon wonderfully well. Textbooks should be as readable.

It is estimated that one out of seven infants born in the United States today suffers from prematurity or associated problems. The incidence of such births varies by region and income, but the advent of neonatal intensive care nurseries in the past 20 years has yielded significant improvements in the chances for babies born at risk. Colen cites these "Metropolitan" statistics for small preemies: In 1970 only 14 percent lived; in 1976, 41 percent made it. The technological offspring of the rubber feeding tube are making a difference.

But are they making enough difference? I can remember many nights as a pediatric resident spent keeping a tiny baby alive with a respirator and droplets of I.V. antibiotics and wondering what chance the child had of growing up normally. Were we not battling against Darwin? The evidence, as cited by Colen, is controversial and inconclusive. Clearly, we are doing better than we used to in minimizing neurological damage in preemies. aAt the same time, though, we are working to save smaller and smaller infants whose chances of sustaining brain damage are greater. The results are hard to measure.

The quandary is addressed well by Colen. "Jim Hannan liked to remind anyone who would listen that the sickest babies represented only the tip of the iceberg. A commitment by society to care for those who seemingly had the the poorest chance of survival inevitably filtered down into better care for those who started off with a better chance. And conversely, a social attitude that denied help to the weakest often denied help to those not so weak, who could derive even more benefit from the help."

"Born at Risk's" greatest shortcoming is an effort to oversell itself. There is a self-conscious swagger -- a touch of machismo -- that starts with an introduction that gratuitously assures us that neonatologists "are not gods." At times, Dr. Hannan comes across as so tough and earthy -- a General Patton among the isolettes -- that I had trouble believing him. Divorced and remarried, he spends his nights in the intensive-care nursery and his weekends with buddies in the back country. I would have liked to know more about Colen's insight into the personal trials of the neonatologist.

"Born at Risk" treats an important and little-publicized corner of the medical world -- and does it well. It will be especially poignant to anyone whose child has spent time in an intensive-care nursery. The mother of a premature infant writes in the preface, "I hope that, somehow she [her daughter] will not forget the other side of her birth experience: the gentle hands, the smiling faces, the friendly voices, the warmth and caring of all the nurses and doctors whose dedication brought her home to me.

"I know I never will."