Patterns of hair loss
The most common type of hair loss in women, accounting for over 95 per cent of cases, is androgenetic alopecia, or female pattern baldness. There's a large genetic predisposition, which may be inherited from the father or mother.
The cause of hair loss in this condition is a chemical called dihydrotestosterone, or DHT, which is made from androgens (male hormones that all men and women produce) by the action of an enzyme called 5-alpha reductase. People with a lot of this enzyme make more DHT, which in excess can cause the hair follicles to make thinner and thinner hair until they eventually pack up completely.