Prenatal hair development: Implications for drug exposure determination

Neonatal hair is a clinically important toxicological matrix, as it allows determination of in utero drug exposure. This paper serves to review the physiological development of the hair follicle and hair production during fetal life. An understanding of the mechanisms and timing of hair development in the prenatal period is critical to effectively assessing the time window of exposure determination associated with toxicological analysis of neonatal hair.