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Introduction Stretch marks are lines on the skin that start off as raised red lines. They then turn purple, before slowly fading into flat silvery streaks. The medical name for this type of mark is stria. Stretch marks happen when the skin is stretched a lot over a short period of time, such as during pregnancy. The skin is made up of three parts: the epidermis (outer layer), the dermis (middle layer), and the subcutaneous (inner layer), where fatty tissue is stored. The dermis helps to support the skin and keep it firm. It also contains blood vessels that supply skin cells with nutrients, and nerve cells that give us feeling. Stretch marks occur in the dermis. The dermis is made up of strong fibres that connect to each other and allow the skin to stretch as we grow. Over time, these small fibres become thinner and less elastic (stretchy), and some of them break. Where the fibres break, the skin becomes thinner, and these areas show as stretch marks. When the skin is stretched thinly, the blood vessels under the surface show through, which is why stretch marks look reddish in colour.
Symptoms Stretch marks appear where the skin has been stretched over a short period of time, such as during a childhood growth spurt or when pregnant. Stretch marks start as red lines on the skin that are slightly raised. Depending on the colour of your skin, they may also look pink, reddish brown, or dark brown. The lines then change to purple, before slowly flattening out. As the lines get flatter, they also fade, and usually end up a few shades lighter than your natural skin tone. Stretch marks usually appear in parallel lines. The skin is thin and silvery and often looks scar-like. They usually fade and become less noticeable over time, but this can take years. Stretch marks can appear anywhere on the body where the skin has been stretched. They usually occur on parts of the body where fat is stored, such as the abdomen, breasts, upper arms, thighs and buttocks. People who put on a lot of weight over a short period of time often notice stretch marks in these places.
Causes Stretch marks occur when the skin is stretched suddenly. The outer layer of skin isnt affected, but the dermis becomes thinner and develops tiny tears. The blood vessels that lie under the skin show through, giving the marks a reddish colour. Later, when the blood vessels contract, the purplish colour fades to silvery white. Stretch marks appear most often in the following cases: Pregnancy: Between 75 and 90% of women develop stretch marks during pregnancy. As you put on weight, the abdomen (stomach) is gradually stretched further and further, usually causing stretch marks to appear in the sixth or seventh month. Stretch marks can also appear on the thighs, and on the breasts as they get bigger and heavier. Adolescent growth spurt: Boys and girls tend to grow very quickly during puberty. Boys often get stretch marks on the shoulders, and girls get them on the hips, thighs, and breasts. Athletes: Athletes who train their muscles to get bigger and stronger over a short period of time sometimes get stretch marks. This is particularly common in bodybuilders. Weight loss or gain: Putting on a lot of weight over a short period of time can cause stretch marks to form. If you are constantly on and off diets, stretch marks can also form, as your weight goes up and down rapidly. If you are dieting, it is important to lose weight slowly so that strain isnt put on the skin. However, not everyone gets stretch marks. Doctors think some people get stretch marks because their bodies produce more of the hormone, corticosteroid, than normal. This hormone decreases the amount of collagen in the skin. Collagen is a type of protein in the fibres of the skin that keeps it stretchy. Occasionally, stretch marks can be a symptom of Cushings syndrome, a condition caused by too many steroid hormones. For more information, please see the separate encyclopaedia entry on Cushings syndrome.
Diagnosis Stretch marks are not harmful and there is usually no need to consult your GP about them. However, if the marks are unsightly and they are making you unhappy, it is worth seeing your GP to discuss treatment options. You should also see your GP if the appearance of stretch marks doesnt seem to be linked to growth or weight changes, as stretch marks can be a symptom of Cushings syndrome.
Treatment There is no specific treatment for stretch marks. Most stretch marks fade over time and arent that noticeable. However, if you have a lot of stretch marks, if they affect a large part of your body, or if you are worried they look unsightly, the following treatments may help: Moisturisers and creams: In the early stages, stretch marks can sometimes be reduced with over-the-counter moisturising creams, particularly those containing vitamin E or vitamin A. Creams containing alpha hydroxy acids (AHAs) are made with plant extracts and can also help. Clinical studies have not proved that these sorts of creams can prevent stretch marks, but they may improve the look of stretch marks in the short-term. Using these types of cream daily can help to keep the skin supple, and the action of rubbing in the cream can encourage better circulation. Tretinoin, or Retin-A: These types of cream are derived from vitamin A and are available on prescription. They make the outer layer of skin thinner, so that the cream can get to the dermis, where it increases the amount of collagen produced. These creams shouldnt be used without advice from your GP because they can cause side effects. Strong doses can cause the skin to sting, swell and become red, and may also make it more sensitive to sunlight. The skin may also get thicker because of the increase in the amount of collagen produced.Tretinoin is not recommended for use in pregnancy or while breastfeeding. People taking Retin-A should avoid taking vitamin A supplements at the same time.
Laser surgery: Laser surgery does not remove stretch marks, but it can help them to fade. Laser treatment for stretch mark is not available on the NHS and is usually very expensive. Laser treatment only picks up dark areas of skin, so it most useful in the early stages when stretch marks are darker in colour. A series of treatments are usually necessary for visible results, but this depends on your skin colour and type. Surgery: An operation called an abdominoplasty is carried out to remove excess fat and skin around the abdomen (stomach), and remove stretch marks below the belly button at the same time. Surgery is a very expensive and extreme option. It is not available on the NHS and is rarely recommended.
Prevention It is important to maintain a healthy weight. Putting on a lot of weight and diets that cause your weight change rapidly, especially over a short period of time, can cause stretch marks to form. If you are trying to lose weight, aim to do it slowly. Massaging your skin everyday with moisturiser or a massage glove can help to improve circulation, which encourages new tissue to grow. It is also important to eat a balanced diet rich in vitamins, especially vitamin E, vitamin C, zinc and silica that help to keep skin the healthy. When you are pregnant, it is normal and healthy to put on weight, but it is a myth that you need to eat for two. Pregnant women need to take in extra calories to nourish the unborn baby, but it is important that these calories come from a well balanced diet. Weight gain while pregnant should happen slowly and gradually. As a rough guide: It is normal to gain 1 to 2kg (2 to 4.5 lb) over the first 12 weeks, From week 12 to 28 it is normal to gain 300 to 400g (10 to 14oz) per week, and From weeks 28 to 40 (the last 3 months) it is normal to gain 1 to 3kg (2 to 6lb) per month. See your GP, midwife or health visitor for advice if you are worried that you arent gaining weight at the correct rate.
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