CAUSES OF STRETCH MARKS
Stretch marks are caused by exactly what their name suggests - stretching. The skin's natural elasticity is provided by collagen and elastin in the dermis. Collagen and elastin are made up of proteins and are key components of the body’s connective tissue. This connective tissue enables the dermis to adapt to continuous movement of the body by expanding and contracting as it changes. During periods of sudden weight gain or loss the skin may have insufficient time to adjust, causing internal tears in the skin tissue which form the scars known as stretch marks.
The likelihood of developing stretch marks varies according to skin type, age, heredity, diet and hydration of the skin. Typically, stretch marks tend to occur under the following conditions:
Puberty. As the adolescent body goes through rapid growth cycles stretch marks can develop.
Pregnancy. Stretch marks are common during the later stages of pregnancy as the abdomen expands to accommodate the growing baby.
Rapid weight gain/muscle growth. If weight or muscle mass is significantly increased over a short period of time stretch marks may become apparent.
Certain medical conditions. Stretch marks can be a symptom of an underlying medical condition such as Cushing's syndrome and Marfan syndrome. Cushing's syndrome causes stretch marks by overproduction of the hormone cortisol which weakens the skin. Similarly, Marfan syndrome causes stretch marks as it weakens the body's connective tissue due to a defective gene. Ehlers-Danlos syndrome (EDS) is a rare inherited condition that affects structural proteins, weakening connective tissue in the skin which can also cause stretch marks.