Stretch marks - what the experts say
How stretch marks form
Stretch marks appear in 3 stages:
Pregnancy hormones and the stretching of skin stimulate the skin’s fibroblasts and cause an inflammatory response. The fibroblasts modify their activity, producing more collagen in particular.
The inflammatory substances and aggressive enzymes that are secreted attack the structure of the skin’s connective tissue; elastin fibers decrease in number, collagen fibers become more dense and narrow, and the overall framework falls into disarray.
As a response to these forms of aggression and inflammation, the skin synthesizes new supporting fibers intended to replace those that were damaged. The repaired fibers are not identical to the old ones, however; the new fibers are more fragile, thinner, fewer in number, and less structured. The initial skin tissue is thus replaced by thinner scar tissue. Thinner and looser, the skin then forms hollows comparable to scars, which are the stretch marks.