Stretch marks are narrow, streak-like lines that can develop on the surface of the skin. They're also sometimes known as stria or striae. Stretch marks are often red or purple at first, before gradually fading to a silvery-white colour.
The structure of the skin
The skin is made up of three main layers, which are described below.
- The epidermis: the outer layer of skin that forms a protective barrier for the inside of your body.
- The dermis: the strong, supportive middle layer of skin that gives the skin its firmness and flexibility.
- The subcutis: also sometimes known as the hypodermis. It is the inner layer of skin, consisting of fat and connective tissue.
Stretch marks occur in the dermis, when the skin is stretched considerably over a short period of time. This rapid stretching causes the dermis to break in places and allow the deeper layers of the skin to show through, forming stretch marks.
Who gets stretch marks?
Anyone can get stretch marks and they are very common, although they tend to occur more often in women than in men. The areas of the body most commonly affected by stretch marks are the abdomen (stomach), the buttocks and the thighs.
Stretch marks can appear on the skin wherever it is stretched as a result of sudden growth, such as during pregnancy, weight gain or growth spurts during puberty.
In some cases, stretch marks can also be a symptom of an underlying health condition, such as Cushing's syndrome.
Cushing's syndrome is caused by an excess (over-production) of steroid hormones. The condition has several associated symptoms, such as weight gain and high blood pressure (hypertension), which are the result of the body producing too much of a particular hormone.
