Stretch marks are a form of scarring on the skin that may fade with time, but seldom disappear all together. The medical term for stretch marks is striae. Most stretch marts first appear as red or purple lines in the skin gradually fading with time to a pink, white or cream color. Stretch marks are most likely to occur on parts of the body where fat is stored such as hips, breasts, abdomen, upper arms, thighs and buttock.
What is the cause of stretch marks?
Stretch marks are caused by the middle layer of the skin, the dermis, tearing which creates scar tissue. This layer of skin is responsible for maintaining the shape of the skin over the body. The tearing is caused by hormones, specifically the glucocorticoid hormones. These hormones prevent the fibroblasts in the dermis from forming collagen and elastin fibers, which are two very important substances for maintaining the stretch and elasticity in skin. Skin that is less elastic is more likely to tear as it cannot support changes in body shape and size.
Some of the most common causes of this tearing are rapid weight gain, rapid muscle gain and the use of steroid creams or oral steroids. Rapid weight gain may occur during puberty or pregnancy. These two life occurrences also signal an increase in hormones such as the glucocorticoid hormones. As the body rapidly changes shape or gains weight the dermis layer of skin is unable to support the extra weight and tears causing stretch marks. Rapid muscle growth such as that experienced by body builders can also cause the development of stretch marks. The changing shape of the muscle puts extra pressure on the dermis creating tears. The use of steroids also effects the development of collagen and elastin fibers in the skin leading to stretch marks.