A number of things can cause hair loss.
An illness or major surgery, poor diet can all amount to hairloss aswell as stress.
This hair loss is normally temporary.
Hormonal problems may cause hair loss.

Many women notice hair loss during pregnancy and is normally only temporary.
If you wear pigtails or use tight hair rollers, you are pulling which can also cause hairloss .
If you stop the pulling before scarring of the scalp develops, then your hair will grow back normally.
Hot oil hair treatments or chemicals used regular on your hair may cause inflammation of the hair follicle, which can also result in scarring and hair loss.

Preventing hairloss is what is important so avoid pulling on your hair, putting your hair up constantly and avoid harsh chemicals and hot oils.

Try and use a magnet hairbrush to promote healthy hair growth as it stimulates the blood supply to the scalp.