Stretch marks (striae) are indented streaks on the body that typically appear on the stomach, breasts, hips or bottom. They occur when the dermis (the thickest layer of skin) has to stretch quickly due to rapid weight gain or a growth spurt.
They're very common in pregnant women, especially during the last trimester, but they can occur anytime the skin becomes overstretched, such as rapid growth spurts during puberty or when bodybuilding.
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