Stretch marks, or striae, are scars that appear on your skin, mainly around the stomach, hips, breasts, upper arms, thighs, and lower back. Stretch marks appear when the skin stretches faster than it can grow. It develops in the middle layer of your skin, called dermis which is responsible for retaining the general shape of the skin. When the underlying tissue grows faster than the dermis, the dermis tear, causing linear striations where the dermis and the upper layer of skin known as epidermis are thinned. Although Your skin is incredibly flexible after a certain point it cannot stretch without tearing and scarring.
The tear also causes tiny blood vessels in the skin to break, giving the stretch mark its characteristic pink or purple hue. During its appearance stretch marks can give a burning or itching sensation. Although stretch marks are not harmful, they are generally unlikable and may cause emotional pain and embarrassment. Unfortunately; stretch marks remain on a person's body forever, even after pregnancy or losing weight.
Fast growth during puberty which manifests with horizontal stretch marks on the upper arms, thighs, and buttocks.
Fast weight gain in which the deposition of subcutaneous fat causes vertical stretch marks on the abdomen
Bodybuilding, in which the quick growth of muscle will develop stretch marks along the perimeter of a muscle.
Pregnancy is the most predominant cause of stretch marks in women. During the later stage of pregnancy, a woman's abdomen is quickly expanding to accommodate a growing baby, stretch marks appear by changes in the elastic supportive tissue just beneath the skin
Hormonal imbalances have been mentioned as one of the main causes of stretch marks. Hormonal changes may occur during puberty, pregnancy, obesity and also weight lifting, it's difficult to guess which particular factor is to blame for the occurrence of stretch marks. . The hormonal imbalance during any of these times can cause collagen and elastin fibers to tear over the stretched skin, creating the appearance of stretch marks.
Apart from these, there are certain health issues that can cause stretch marks.