What is Stretch Marks in Pregnancy?

Stretch marks are streaks that appear on the skin as it stretches to accommodate a growing bump, most commonly on the belly, breasts, hips, and thighs. They happen when the skin stretches faster than its natural elasticity can accommodate, causing small tears in the deeper layer of skin.

They're extremely common in pregnancy — affecting a large majority of people to some degree — and are largely determined by genetics and skin type rather than anything that can be fully prevented. They typically fade from reddish or purple to a lighter, silvery colour over time after birth, though they don't usually disappear completely.