Stretch marks, also known as "striae," are discolored streaks or indentations of the skin on the abdomen, breasts, buttocks, arms, legs and thighs. Often, they appear in the third trimester of pregnancy, but can be associated with other medical conditions. Stretch marks are harmless and generally fade to a lighter color or disappear entirely.
Pregnancy-associated striae are the result of the rapid stretching of the mother's skin and an increased level of a hormone called cortisol. Cortisol is produced in the adrenal glands and increased levels of the hormone help the pregnant woman deal with the stresses of pregnancy. However, cortisol also weakens elastin fibers in the skin, making it more fragile and susceptible to damage. As the mother's belly swells to accommodate her baby, her fragile skin sustains some damage. However, as hormone levels in the post-partum woman drop to normal, the striations fade.
Adolescents may notice a few stretch marks with the onset of puberty and sudden growth. Weightlifters can also develop stretch marks, particularly on the arms and thighs as they build muscle mass. Finally, non-pregnancy, sudden weight gain can lead to stretch marks. In all three cases, the striations are harmless and fade as the skin adjusts.
Stretch marks can also be a symptom of other conditions. For instance, Cushing's syndrome and other diseases related to the adrenal gland can cause stretch marks to develop all over the body. The stretch marks are the result of elevated circulating levels of cortisol in the body. Cortisol weakens elastin fibers in the skin that make it pliable and smooth. Marfan syndrome and Ehlers-Danlos syndrome, both hereditary connective tissue disorders, can also cause stretch marks.
Although stretch marks are harmless, some may find them a cosmetic concern. Several options are available to help to reduce the appearance of striations. Tretinoin cream can be used to treat recent stretch marks. It works by promoting the production of collagen in the skin. Tretinoin cream is not safe for use during pregnancy. Several types of laser treatment are available that are more effective for older stretch marks. Laser therapy stimulates the production of elastin and collagen in the skin, increasing its flexibility. Another option is microdermabrasion--a treatment which sloughs off the top layer of skin and encourages new skin growth.
Moisturizing the skin during pregnancy will help it stay pliable and minimize damage. The best remedy for stretch marks after a pregnancy, however, is exercise. Firm stretched tissues with a basic regimen of core, thigh, calf, glute and arm exercises to return to pre-pregnancy shape.