Hematologic disorders is the topic for this issue of JPNN. Many of these disorders can be devastating for infants, mothers, and families. Each article in the perinatal section discusses the genetics of the disorder and its prevalence in diverse populations. The authors review the controversies surrounding screening women for rare disorders, including benefits and costs. Awareness of the effects of hematologic problems and the ability to formulate a plan of care for her patients-the fetus, the infant, and the mother are discussed.

One of the more common hematologic disorders is Rh incompatibility. Harrod, Hanson, VandeVusse, and Heywood use a case-based approach to explore Rh incompatibility. They review the use and controversies regarding Rho (D) immune globulin, along with several scenarios for management of the sensitized pregnancy. Evidence for administration of Rho (D) immune globulin prentatally and during the postpartum period is presented.

Sosa presents an overview of autoimmune thrombocytopenia. Autoimmune thrombocytopenia is a complex condition with many acronyms and genetic markers. The disorder is often not diagnosed until after an affected infant is born. She delineates the arguments for and against universal screening for autoimmune thrombocytopenia and presents protocols used in a current research program for treatment of autoimmune thrombocytopenia.

Ament reviews current literature on Factor V Leiden disease. She also discusses screening protocols for this hematologic disorder and presents a table of risk factors that can provide nurses with a suspicion index during history taking. Nurses will rarely encounter either of these disorders but must be prepared if they do. Nursing literature rarely discusses these conditions.

Poole discusses thalassemia and pregnancy. Thalassemias are the most common of the genetic blood disorders. She explains the different types of thalassemias and provides a table delineating laboratory results commonly found with this disorder.

Polycythemia and hyperviscosity are disorders whose presentation is often subtle and are seen most frequently in term or near-term infants. Diagnosis and treatment of polycythemia are often controversial. The nurse is often the person to identify subtle signs of these disorders. Gordon in her article discusses the etiology, pathophysiology, assessment, and diagnosis of polycythemia and examines current treatment issues surrounding management of this disorder in the neonate.

Hyperbilirubinemia is a common hematologic problem in the neonatal period, affecting both term and preterm infants. Although short-term side effects have generally been shown to be benign, there have been little work on longer term effects and in particular on entrainment and development of biological rhythms. Building on their previous work on development of sleep-wake rhythms in infants and children, Shimada and her colleagues examined the effects of phototherapy during the neonatal period on development of circadian sleep-wake patterns and on salivary cortisol in early infancy and in the young child.