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What causes stretch marks during pregnancy?

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Close-up of a home pregnancy test device showing a blue plus sign in the result window, indicating a positive result for pregnancy. — pregnancy Devices for individual use at home detect pregnancy by measuring levels of the hormone human chorionic gonadotropin (hCG) in urine.

During pregnancy, stretch marks occur due to the tearing of elastic tissues within the skin. This damage is caused by the physical enlargement of the breasts, the distention of the abdomen, and the deposition of subcutaneous fat.1

While these marks often appear as pink or purplish red lines during pregnancy, they typically fade into permanent, scar-like marks after delivery. It is important to note that susceptibility to these marks varies significantly between individuals; some women may not develop them at all, while others experience a loss of skin tone. Furthermore, because they result from the rupture of elastic fibers due to excessive stretching, they can also occur in individuals who have not been pregnant, such as those experiencing rapid weight gain or obesity.12