What are stretch marks and how do they develop?

Stretch marks are caused by excessive stretching of the subcutaneous connective tissue. The collagen fibers are stretched and the elastin fibers are broken.

Because the process is slow, the top layer of your skin remains intact, but the texture becomes different. At first, the stretch marks look red or reddish brown, later (months to years) this changes to a lighter beige or skin-colored shade.

Striae distensae can occur anywhere where the skin is stretched too much in a short period of time. The main causes are pregnancy and lactation (stomach and breasts, striae gravidarum), and the growth spurt during puberty (especially thighs, buttocks, lower back and breasts). It is also seen in obesity (stomach, thighs, inner thighs, upper arms), in bodybuilders (arms, thighs, breasts), and in breast enlargement.

We also see stretch marks appear during the growth spurt in puberty, these are not associated with being overweight. These stretch marks often run on the lower back and horizontally.

In addition, stretch marks can occur as a result of collagen fiber weakness due to long-term use of topical or systemic corticosteroids, or due to excess internal adrenal cortex hormone (cortisol) production. This variant is called striae atrophica and can occur without excessive stretching.