Stretch marks develop on parts of the body experiencing rapid growth, for example during growth spurts as a teenager or throughout pregnancy. Common areas that people develop stretch marks are: the stomach, upper arms, buttocks, thighs, breasts and shoulders (in bodybuilders).

Telltale signs that you are developing stretch marks are: the skin feeling stretched, thin and becoming increasingly itchy. As the skin stretches, the middle layer of skin called the dermis tears, allowing the deeper skin layers to show through as thin purple lines. As stretch marks grow older, they go from thin, purple lines to silvery-white ones.

Pregnancy is one of the most common times of a woman's life that stretch marks appear. They usually appear in the later stages of pregnancy, and often emerge across the tummy as it grows, or across breasts and thighs.

Rapid weight gain in any area of the body can also result in having stretch marks. Common factors resulting in weight gain include: the ageing process (where muscle mass tends to become less), diabetes treatment, steroid treatment, excess tiredness and numerous hormonal imbalances.