Stretch marks

What are they?
Stretch marks look like thin, stretched tissue, and that is more or less what they are. They appear in people who put on or lose weight rapidly. The upper layer of the skin is normal, but in the lower layer the collagen and elastin, which give the skin its strength and elasticity, have become thinner and broken. At first, the marks look reddish-purple. This is because the stretched skin is more transparent and the small blood vessels that lie deep in the skin show through. Later, the blood vessels contract. The purplish colour then fades to white, which is simply fat under the skin showing through.

Who gets them?

• Stretch marks often appear on the breast and abdomen during pregnancy. The reason is partly hormonal. During pregnancy, hormones have the job of softening the collagen ligaments of the pelvis, so that the tissues can stretch easily during childbirth. Unfortunately, the skin collagen softens as well, allowing stretch marks to form easily.
• Some women have weaker collagen than others, so are more likely to get stretch marks. Recent research suggests that if you have stretch marks, your pelvic floor ligaments may be slightly weak, so it is very important to do pelvic floor exercises after childbirth to prevent incontinence of urine.
• Yo-yo dieters and bodybuilders can get stretch marks on the upper arms, chest and thighs.
• Growing adolescents can get them on their backs, where they look like a series of horizontal lines.

Preventing stretch marks
Try to avoid yo-yo dieting. If you are overweight, aim to lose it slowly (do not aim to lose more than 0.5 kg (1 lb) a week).

If you are pregnant, there is not much you can do except keep your fingers crossed and think, “this is a small price to pay for a beautiful baby!” Rubbing baby oil into the abdomen each night might help. Various special creams and oils are promoted for preventing stretch marks, but there is no proof that they are effective.

Curing stretch marks
Stretch marks are permanent in the sense that the skin in these areas will never be completely normal. However, after a time they contract down into much less obvious, thin, whitish scars.

Collagen creams claim that they will improve stretch marks. There is no evidence that they do so. In fact, collagen and elastin put onto the surface of the skin can not penetrate into the deeper layers.

Cocoa butter cream, which is available from pharmacies, is often recommended to soften scars, so might be worth a try.

Lasers can be used to treat stretch marks at an early stage, when they are still red. The red blood cells in the small blood vessels absorb the energy from the laser beam and convert it into heat, which then seals the blood vessels. This gets rid of the red colour and might speed up the contracting process, but is uncertain whether it will make any difference in the long run.

It costs several hundred pounds, and can not be done under the National Health Service in the UK. As with any cosmetic treatment, check that the clinic is reputable; your doctor can probably advise you, and look at the section on cosmetic surgery.

Tretinoin is another approach to the treatment of early stretch marks. There have been claims that this produces improvement, but other researchers have not found any effect (Cutis 1994;54:121–4).

Surgery is a possibility for tummy stretch marks if you also have a lot of loose skin on the tummy. The operation is a ‘tummy tuck’ (removal of the skin and the fatty tissue beneath). You will be left with scars around the belly button and across the lower stomach. This is not a minor operation and, like all operations, it carries risks. Recovery takes several weeks. Look at the section on cosmetic surgery.