There is no time in life when human physiology changes more rapidly than in the neonatal period. The blood is very much affected by the transition from the intrauterine to the extrauterine environment. During this time, the normal range becomes a moving target, making it difficult to distinguish many abnormalities from physiologic variations. Furthermore, remarkable advances in perinatal/neonatal medicine have led to dramatic improvements in infant survival – now extending to the extremely low-birthweight infant. Many previously fatal congenital disorders are no longer universally so, due both to advances in basic and clinical research and to the hard work of perinatologists, neonatologists, pediatricians, pediatric subspecialists, and surgeons.

Melissa Warfield, M.D., a pediatric hematologist of great experience, would refer to textbooks as either “How come?” books or “How to” books. It is the goal of this textbook to be a “How to” book, with some discussion of the pathophysiology of the hematologic problems while focussing on practical aspects for the clinician. While there is some overlap between each of the areas covered in this book, as there is with most of the hematologic disorders of the newborn, we have chosen to be inclusive of the discussions prepared by each of the contributors.

The contributors to this text bring a wealth of knowledge and expertise to each of the chapters. We are so fortunate to have readily acknowledged experts with a wide range of backgrounds, including neonatologists, pediatric hematologists, pediatric immunologists, pediatric transfusion medicine specialists, and pediatric infectious diseases physicians.