Scalp hair characteristics in the newborn infant

Scalp hair growth and patterning are closely associated with the development of the central nervous system. A number of genetic, metabolic, and neurologic disorders are associated with recognizable scalp hair abnormalities. For this reason, a systematic step-by-step assessment of the hair and scalp should be an integral part of every initial newborn physical assessment. This article reviews the clinically relevant embryology related to fetal scalp hair formation. Normal cycles of hair growth and loss are discussed. A systematic review of typical newborn scalp hair characteristics such as color, quantity, texture, direction of growth, hairlines, and hair whorls is provided. Conditions associated with abnormal hair color, quality, quantity, and distribution are presented in a series of clinical photographs, and their salient features are discussed. Abnormal hair often occurs as a constellation of findings; implications for clinical care and further investigation will be briefly described.