
A number of things can cause excessive hair loss. For example, about three or four months after an illness or major surgery you may suddenly lose a large amount of hair. This hair loss is related to the stress of illness and is temporary.
Hormonal problems may cause hair loss. If your thyroid gland is overactive, or are less active than normal hair can fall out. This hair loss usually can improve with treatment of thyroid disease. Hair loss may occur if there is a balance of male or female hormones known as androgens and estrogens. Correcting the hormone imbalance may stop the hair loss.
Many women find that they lose hair at three months after having a baby. This loss is also related to hormones. During pregnancy, high levels of certain hormones cause the body to keep hair that would normally fall. When the hormones return to pre-pregnancy levels, that hair falls out and the normal cycle of growth and hair loss starts again.

