Due to hormonal changes, irritation or damage, some hair follicles have a shorter growth phase and produce thinner, shorter hair shafts. Your hair goes through a cycle of growth and rest. The course of each cycle varies by individual. So why do women lose hair - are the causes very different to those that result in male baldness?

1. Hormonal changes. Hormonal changes and imbalances can cause temporary hair loss. This could be due to pregnancy, childbirth, discontinuation of birth control pills, the onset of menopause, or an overactive or underactive thyroid gland. The hair loss may be delayed by three months following a hormonal change, and it'll take another three months for new hair to grow back. During pregnancy, it's normal to have thicker, more luxuriant hair. It's also common to lose more hair than normal about three months after delivery. If a hormonal imbalance is associated with an overproduction of testosterone, there may be a thinning of hair over the crown of the scalp. Correcting hormonal imbalances may stop hair loss.

2. Scarring Alopecia can be caused by a variety of medical or dermatologic conditions such as Lupus, Lichen Planus, or local radiation therapy. Hair loss from injuries, or from local medical problems that have been cured, are usually amenable to hair transplantation. Radiotherapy can cause both scarring and non-scarring localized hair loss and it also can be treated with surgical hair restoration if the area is not too large.

3. Alopecia areata - this is the third most common hair loss condition to affect women. It is characterized by patchy areas of hair loss on the head or it can be more widespread over the body. It is thought to be caused by deficiencies in the immune system but much is still not known about the condition. In many cases the hair regrows spontaneously after a variable period of time, but in a minority of cases the problem may be more severe and longstanding.

4. Insufficient protein in your diet may result in protein malnutrition that can affect hair loss. If you are on a diet that is low in protein this may be the culprit. Your body will take the protein from your hair, forcing your hair into the telogen or resting phase. Hair loss will then occur two or more months later. This is not permanent hair loss and can be reversed with a proper diet with healthy amounts of protein.

5. Hair treatments. Chemicals used for dying, tinting, bleaching, straightening or permanent waves can cause hair to become damaged and break off if they are overused or used incorrectly. Overstyling and excessive brushing also can cause hair to fall out if the hair shaft becomes damaged.

6. A relatively large number of drugs can cause "telogen effluvium," a condition where hair is shifted into a resting stage and then several months later shed. Fortunately, this shedding is reversible if the medication is stopped, but the reaction can be confused with genetic female hair loss if not properly diagnosed. Chemotherapy causes a diffuse type of hair loss called "anagen effluvium" that can be very extensive, but often reversible when the medication is stopped.

7. Medical treatments can cause hair loss. Often treatments for conditions such as cancer can cause hair loss. Some cancer treatments cause the hair cells to stop dividing. The hair then becomes thin and weak breaking as they emerge from the scalp. This can begin occurring one to three weeks after treatment has started. Hair will usually begin to grow again after the treatment has been completed.