Stretch marks and how they appear

Stretch marks, also called striae, are narrow, streak-like depressions of the skin that form in areas of dermal damage produced by stretching of the skin.

They're very common and usually develop between the ages of five and 50 years.

Striae are twice as common in females as males and up to 90% of pregnant women will develop stretch marks.

How do they develop?
Firstly, it's important to understand the structure of the skin to know how stretch marks are produced.

The skin consists of three layers:

- The outermost layer is called the epidermis and forms a protective barrier for the inside of the body. This layer consists mainly of several layers of flat cells, which become progressively smaller and are shed in a regulated manner. 
- The dermis is the middle layer of the skin, which consists of blood vessels, collagen and elastic tissue. This layer provides support, firmness and flexibility to the skin.
- Finally, the subcutis, which consists mainly of fat and connective tissue,helps in keeping the skin glued to the muscles and fascia of the body.

As the skin is stretched considerably over a short period of time, the collagen fibres and elastic tissues in the dermis become strained and finally break. This leaves small gaps that allow the deeper layers of the skin to show through, forming stretch marks.

As the capillaries and small arteries show through the gaps, the striae first appear as red, purple or dark brown streaks on the surface of the skin. They're slightly raised and may feel wrinkly. With time, the lines become flatter and slowly start fading away, leaving some remnants behind. They can leave patches of parallel lines behind that may look thin and silvery and can often look scar-like.

Areas that are most commonly affected are the abdomen, buttocks, thighs, upper arms and breasts (in women).

What are the causes of stretch marks?

  • Pregnancy

Most pregnant women will develop stretch marks. There are two mechanisms by which pregnant women develop these striae:

1.) As the baby grows, the skin of the tummy is stretched further and further and this leads to breaks in the collagen.
2.) The stretch marks also develop on the thigh and breasts, as they become bigger and heavier.

During the second trimester, some hormones are also produced to soften the ligaments in the pelvic region and to facilitate delivery of the baby. However, these hormones also soften the collagen in the dermis, making the pregnant woman more prone to stretch marks. They occur more during the first pregnancy and one study has shown that the amount of stretch marks during pregnancy can be a predictor for vaginal lacerations during delivery. More recently, the presence of striae was found to be a risk factor for the development of pelvic relaxation and clinical prolapse.

  • Puberty

During puberty, the body tends to grow very quickly. This can put added strain on the collagen in the dermis, leading to breaks. As a result, males often get stretch marks on their shoulders and back, and females get them on their hips, thighs and breasts.

  • Rapid weight gain

Striae develop if you put on a lot of weight over a very short period of time. The stretch marks will fade over time. Dieting can also result in stretch marks if your weight fluctuates rapidly. It's important for slimmers to lose weight slowly and steadily. In this way, you don't put the skin under added strain.

  • Family history

Stretch marks can also be familial. If you have first-degree relatives who are affected, you're more prone to getting these striae. They can also affect both men and women.

  • Corticosteroids

Both topical creams and oral corticosteroids can result in the formation of stretch marks. These can even affect the face, joints and areas less commonly affected by weight gain. The corticosteroids decrease the collagen fibres in the dermis and also affect wound healing. This causes the skin to thin and become less pliable, leading to the formation of stretch marks.

  • Health conditions

Certain diseases can make you more prone to stretch marks. Cushing’s syndrome occurs when the body produces an excess amount of cortisol. This leads to central obesity, weight gain, increased bruising and the formation of stretch marks. Other conditions like Marfan’s syndrome tend to affect the collagen tissue in the dermis, also leading to the formation of striae.

Is there a magic cure for stretch marks?
There's no specific medical treatment for stretch marks. Most treatment can help improve their appearance, but don't take them away completely. In most cases, they're not particularly noticeable and fade over time. It's best to focus on measures to prevent their formation in the first place.

  1. Putting on a lot of weight, and diets that cause weight to change rapidly, can lead to stretch marks, because the skin is literally stretched by the sudden growth. If you have to lose weight, it must be done gradually. Try to lose about half a kilogram per week.
  2. Massaging the skin with moisturisers helps to improve circulation and encourage collagen growth. It also helps the skin to remain pliable, thus decreasing the extent of stretch marks.
  3. During pregnancy, it's normal to put on a significant amount of weight in a short period of time. Stretch marks will form as a result of hormonal changes. However, they can be minimised by gaining weight steadily. The pregnant woman doesn't need to "eat for two". It's important to follow a balanced diet that's rich in whole-wheat carbohydrates as well as fruits and vegetables. Don't consume more than 2500 calories per day. A normal-weight woman should gain only between 11 - 16kg during pregnancy, and this should be very gradual. Massaging the skin will also increase the production of collagen and decrease the formation of stretch marks.

Treatments available
There are many creams, gels and lotions that claim to be able to remove stretch marks. These are essentially moisturisers, and rubbing them on early stretch marks can increase blood flow, leading to some improvement. However, none of these products will take away the stretch marks completely.

Treatment of early striae with tretinoin creams can help improve their appearance by decreasing their lengths and widths. These are medical creams and need to be prescribed by health professionals. Other topical combinations with glycolic and L-ascorbic can also help.

Laser treatment of extensive striae can help improve their appearance. The laser most commonly used is the 585nm pulsed dye laser. It helps only during the early stages.

Cosmetic surgery for striae is very expensive and rarely recommended. The operation is called a "tummy tuck", which removes the excess skin and fat around the abdomen, as well as removing the stretch marks below the belly button. This isn't practical for most people.

Stretch marks can be very distressing. The good news is that most will fade with time. There's no need to waste money on expensive creams or oils that claim to help. It's best to consult a dermatologist at an early stage, when treatment may make a difference.

- (Dr R. Newaj, dermatologist)

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