Although medical science has yet to discover the precise factors that make the number-21 chromosomes stick together, leading to the birth of a Down syndrome baby, great strides have been made in the past two decades in recognizing the special needs of children with this birth defect. There also has been much progress in helping parents face the challenges of nurturing their children so they can reach their highest potential.

One indispensable book on this subject is "Babies With Down Syndrome: A New Parents Guide," edited by Karen Stray-Gundersen, herself a parent of a Down syndrome child.

Compassionate, realistic and practical, this 242-page paperback is a compilation of chapters written by parents and health professionals providing a full range of answers to questions on Down syndrome, the baby's development, potential medical programs and treatments and the resources available to help families cope.

Significantly, the book starts with an affectionate and upbeat introduction by Connecticut Sen. Lowell P. Weicker Jr., who describes his 9-year-old son Sonny as lovable (a characteristic that is often attributed to Down syndrome children) and then goes on to list additional traits that are unique to his son: stubborn, resilient, street smart, bossy and open.

This emphasis on the uniqueness of each Down syndrome child is a key theme of the book. It is reinforced by beautiful, sensitive photos.

No attempt is made in the book to play down the initial shock parents feel on learning their baby has Down syndrome -- and the anger, despair, resentment and depression that may follow. These are dealt with realistically as natural reactions and balanced by suggestions on recognizing these feelings and learning how to adjust.

One of the most compelling facets of the book is the "parent statements" section at the end of each chapter -- comments from parents who "have been there" on how they cope and the emotional rewards they reap from watching their child thrive. Here are one parent's comments: "With a normal child, you just expect the development to happen, but with Chris every milestone is a great success. When he crawls or feeds himself with a spoon we're very happy, and we tell everyone about his progress. Other people might think we're going overboard, but we're very proud of every small victory."

In non-technical terms, the book covers an array of medical problems that Down syndrome children are susceptible to, such as heart defects, vision and hearing problems and infections, and underscores the importance of dealing with them as soon as possible. The authors also provide practical information on feeding routines, bathing and skin care, toilet training, exercise, discipline and selecting a pediatrician who is "current in both knowledge and attitude" on Down syndrome.

One parent offers the following insight: "We had a pediatrician who kept saying 'these children,' patting me on the head and telling me not to worry, that this is what life was going to be like and I might as well get used to it. But I decided that I wanted to do everything I could, and I wasn't getting the impression that this doctor was giving me everything I could do . . . It took about a month before it dawned on me to go exploring for someone who would be more positive."

The book strongly advocates keeping the Down syndrome child at home, maintaining that parents are in the best position to rear their child, to help the child grow and to protect his or her rights.

In addition, there are easy-to-understand benchmarks to help parents track their child's development in motor skills, language, cognition and social and self-help areas. It also urges early developmental intervention programs tailored to each child's needs.

Although the book focuses primarily on the early years, its authors show a keen awareness of parents' concerns about their childrens' futures. The final chapter provides information on programs and services that are available to adults with Down syndrome and ways in which parents can protect their children's emotional and financial security, when the time comes that they have to face the future alone.

A more technical but extremely informative work on the subject is "New Perspectives on Down Syndrome," edited, among others, by Dr. Siegfried M. Pueschel, director of the Child Development Center at Rhode Island Hospital in Providence. The textbook-size compendium of papers on various aspects of this birth defect is published by Paul H. Brookes Publishing Co., Baltimore, Md.

Other recommended reading is "Our Brother Has Down's Syndrome," by Shelley, Jasmine and Tara Cairo. This is a colorful photo essay aimed at young siblings. The brochure-sized booklet is published by Annick Press, Ltd., Toronto, Canada.

Tania Demchuk is a public affairs specialist with the National Association of Independent Insurers.