Stretch marks are purple-red streaky scars that appear in overstretched skin. Around half of all pregnant women will develop stretch marks (striae gravidarum), usually in the third trimester, as the abdominal skin is forced to accommodate the growing uterus. Some pregnant women also develop stretch marks on the breasts, hips, buttocks and thighs. Another common cause of stretch marks is rapid weight gain. Depending on the skin type, fresh stretch marks can be pink, purple, brown or red. Over time, the stretch marks lose their bright colouring and become silvery, shimmering lines.
The evolution of a stretch mark includes:
- The skin is stretched beyond its capacity
- The underlying tissue tears
- The body responds by forming scar tissue
- The fresh stretch mark looks pink, red, brown or purple
- Over time, the colour fades
- The stretch mark becomes a shimmering, silvery line
- The silvery line may look slightly indented
- The scar is permanent.
Structure of the skin
The visible layer of skin (epidermis) protects the delicate inner layers. The epidermis is made from several sheets of cells. Epidermal cells born in the bottom sheet push up through the layers to replace old, dead skin cells that are constantly sloughed off the surface. The epidermis also contains melanin, the pigment responsible for skin colour. Beneath the epidermis is the dermis. This deeper layer contains sweat glands, sebaceous glands, hair follicles, blood vessels and nerves. The dermis is made from two types of fibre: elastic fibres (elastin) for suppleness and protein fibres (collagen) for strength.
The overstretched dermis
Skin is remarkably flexible and can stretch substantially if given sufficient time. However, a rapidly growing foetus often means the abdominal skin is stretched further and faster than it can comfortably manage. The overtaxed fibres of the dermis tear at the points experiencing the greatest stress. Another common cause of stretch marks is rapid weight gain. Some people develop stretch marks during puberty, if their growth spurt is particularly fast. Whether or not a person develops stretch marks seems to partly depend on their skin's inherited characteristics. Other causes of stretch marks include corticosteroids and Cushing's syndrome.
Prevention of stretch marks
Research is contradictory but some trials have found significant successes with certain creams. Prevention suggestions include:
- Eat sensibly to avoid gaining excess body fat.
- Eat a highly nutritious diet to maintain the health of your skin.
- Wear a supportive maternity bra throughout pregnancy.
- Consider using creams that include centella asiatica extract, alpha tocopherol (vitamin E) and collagen-elastin hydrolysates
Other skin changes during pregnancy
The skin is affected by the cocktail of pregnancy hormones in many different ways, depending on the individual. Apart from stretch marks, other common skin conditions triggered by pregnancy can include:
- Hyper-pigmentation - patches of dark colouring on the skin, particularly the face (chloasma).
- Hirsutism - an increase in hair on the face and body.
- Varicose veins and broken capillaries - caused by the overburdening of the circulatory system and the side effects of certain pregnancy hormones.
- Pimples and acne - caused by hormonal fluctuations.
Where to get help
- Your doctor
Things to remember
- Stretch marks are purple-red streaky scars that appear in overstretched skin.
- Around half of all pregnant women will develop stretch marks (striae gravidarum).
- Over time, stretch marks lose their bright colouring and become silvery, shimmering lines.