Telogen effluvium: Excessive temporary loss of telogen hair (hair in the telogen, or resting, phase) caused by trauma such as childbirth, surgery, starvation, certain drugs, and high fever. A normal human hair goes through 3 successive stages of growth:
The growing, or anagen, stage is the predominant phase (80% to 90% of a person’s hair is usually in the anagen phase).
A transitional, or catagen, stage.
Resting, or telogen, stage.
When new hair growth is initiated, the new anagen hair pushes the old telogen hair out, and shedding occurs. Typically a person sheds no more than 50 to 100 hairs per day. A severe stress such as childbirth can “shock” an excessive number of hairs into the telogen stage. Approximately 3 months after this stress, the new mother may experience excessive hair loss on the order of 100 or more hairs per day. This excessive hair loss is termed telogen effluvium. Up to 90% of postpartum women experience it. The condition can occur immediately after delivery but, more typically, it occurs between 2 and 6 months’ postpartum. The shedding rate returns to normal in 4 to 6 months.