Medically known by the names of striae distensae, SD, striae, striae atrophicans and striae gravidarum, stretch marks are defined as dermal scars or lesions on the outermost layer of the skin. They present themselves as pink, red or purple lines (indented streaks) often on the hips, abdomen, breasts, upper arms, thighs or buttocks. Over time stretch marks tend to flatten and fade to translucent white or grey pale marks. While both men and women are affected by stretch marks, around 70 percent of adolescent girls develop the condition during puberty compared to 40 percent of boys. Those at higher risk of developing stretch marks include:

• Adolescents during growth spurts or hormonal changes
• Pregnant women
• Body-builders
• Obese or overweight people

Stretch marks are formed is the areas of the body where the skin is subjected to continuous stretching. The skin is divided into three main layers: the subcutaneous or hypodermis (deepest layer), dermis (middle layer) and the epidermis (the outer layer). Stretch marks are formed within the dermis. The rapid stretching of the connective tissue due to sudden growth or weight gain damages the dermal tissue atrophy and causes thinning of the outer layer. This allows the deeper skin layers to be revealed, forming the unsightly streaks along the surface. When the body grows, the connecting fibres of the dermis naturally stretch slowly. However with rapid growth, these fibres are overstretched and tear. This inflammatory reaction within the skin is the responsible for the stretch mark’s red or purple tone (new stretch marks). When viewed under a microscope, the tissue affected by stretch marks resembles that of a scar due to the changes in the collagen fibre’s appearance.