Stretch marks are very common and completely normal. They are a normal part of puberty during growth spurts, and many women develop stretch marks after pregnancy. An estimated fifty to ninety percent of pregnant women develop stretch marks before delivery. They most often appear on the stomach, chest, hips, buttocks, and thighs. Although they are not painful, they can affect self-confidence.
Stretch marks, formally known as striae gravidarum or striae distensae, are caused by tears in the dermis (deepest) layer of your skin that occurs when the skin expands too rapidly. Thus, it is most often seen during pregnancy, puberty, rapid weight gain, and bodybuilding. Although the top surface of the skin remains intact, tears in the dermis eventually heal as permanent scars that become a visible stretch mark. Stretch marks first appear as red or purple, and slowly fade to silvery white with time.