What are stretch marks? How can stretch marks be treated?

Stretch marks are long, narrow streaks, stripes or lines that develop on the surface of the body with an off-color hue. 

They are the result of a sudden stretching of the skin. Stretch marks are extremely common, and anyone can get them, although they tend to affect more women than men.

Stretch marks can be visible on body parts including the tummy, thighs, hips, breasts, upper arms, and lower back. The marks form in the middle layer of the skin; when there is a constant stretch, the layer tears, leaving stretch marks.

This type of scarring happens when the skin cannot bounce back after pregnancy, weight gain, or extreme weight loss. The marks begin with a slightly red or purple shade and then fade, leaving the skin streaked in silvery white lines that may or may not disappear.

Contents of this article:

• What are stretch marks?
• What causes stretch marks?
• Signs and symptoms
• Tests and diagnosis
• Treatment and prevention

You will also see introductions at the end of some sections to any recent developments that have been covered by MNT's news stories. Also look out for links to information about related conditions.

Fast facts on stretch marks

Here are some key points about stretch marks. More detail and supporting information is in the main article.

• Depending on the race and age of the population studied, prevalence of stretch marks can range from 40-90%.
• Both sexes are affected by stretch marks.
• Around 70% of girls develop stretch marks during puberty.
• Around 40% of boys develop stretch marks during puberty.
• Stretch marks can occur during pregnancy, puberty, after rapid weight gain, during various medical conditions and after using certain medications.
• Stretch marks often appear after week 25 of pregnancy.
• Common areas stretch marks are found are the abdomen, breasts, hips, flank, buttocks and thighs.
• Stretch marks are more common in younger pregnant women.
• Cocoa butter is not effective in preventing stretch marks.
• Laser therapy for stretch mark removal has proven effective.

What are stretch marks?

Stretch marks (also called striae distensae, SD, striae, striae atrophicans, striae gravidarum) are considered to be dermal scars or disfiguring lesions, characterized by flattening and atrophy (wasting or degeneration) of the epidermis (the outermost layer of the skin).^1,47

Stretch marks are distinguished by linear, smooth bands on the skin that, depending on skin color, can appear as red or purple that fade over time to leave silvery pale marks.^3,10,34

Stretch marks are long, narrow streaks that are visible on the skin's surface and are the result of a sudden stretching of the skin.

Occurring in 40-90% of women, stretch marks appear following rapid repeated over-stretching of the skin over weak connective tissue. The most common areas affected are the:^{10,46,48,49,55}

• Abdomen
• Breasts
• Hips
• Flank
• Buttocks
• Thighs.

Skin changes are a frequent feature in pregnancy with stretch marks occurring in over 70% of pregnant women, most commonly after 25 weeks of gestation.²⁵

While not medically dangerous, aesthetically, the marks can be a great cause of concern and anxiety for many women, impacting on their quality of life.¹⁰ They can be disfiguring, causing emotional and psychological distress during the latter stages of pregnancy when they are most prominent, and in the postnatal period where they appear pale.^33,40,51

This therapeutically-challenging form of dermal scarring tends to occur during:^47,3

• Pregnancy
• Puberty
• Obesity
• Rapid weight gain
• Weightlifting
• Numerous medical conditions
• And following therapeutic interventions.

Pregnancy

Stretch marks are common during the later stages of pregnancy; occurrence is dependent on skin type and skin elasticity.

Hormones are produced during pregnancy that soften pelvic ligaments and increase their flexibility. Hormones also soften skin fibers, giving an increased risk of stretch marks.

The stretch marks appear on the woman's tummy as the baby grows and can sometimes be found on the thighs and breasts.

Puberty

The body goes through rapid growth cycles during puberty which can cause the development of stretch marks on boys' shoulders and backs and girls' hips, thighs and breasts.

Rapid weight gain

Stretch marks become apparent if weight is gained over a short period or if bodybuilders and athletes increase muscle mass.

Medical conditions

Medical conditions such as Cushing's syndrome and Marfan syndrome can cause stretch marks. Cushing's syndrome causes stretch marks by the overproduction of the hormone cortisol and Marfan syndrome weakens the body's tissue and elasticity due to a faulty gene. 

Ehlers-Danlos syndrome (EDS) is a rare inherited condition that disrupts the integrity of structural proteins in the skin which can also cause stretch marks.

Corticosteroids

Sometimes prolonged or inappropriate use of corticosteroid creams and lotions that are used to treat eczema can cause stretch marks by decreasing the amount of collagen in the skin.

Late-stage faded stretch marks are a type of scar characterized by a loss of collagen - a type of protein fiber found throughout the body, providing strength and cushioning to many different areas, including the skin - and elastic fibers in the dermis. The dermis is the layer of sensitive connective tissue of the skin located below the epidermis, containing nerve endings, sweat and sebaceous glands, and blood and lymph vessels.³⁸

What causes stretch marks?

The skin consists of three key layers: epidermis (the outer layer), dermis (the middle layer) and subcutaneous or hypodermis (the deepest layer). Stretch marks form in the dermis when the connective tissue is "stretched" beyond the power of its elasticity due to rapid expansion or contraction of the skin from sudden growth or weight gain.

The three main layers of the skin are the epidermis, dermis and hypodermis. Stretch marks are caused when the dermis is stretched so rapidly it tears.

The abrupt stretching causes the dermis to tear which allows deeper skin layers to show through, forming the stretch marks.

Usually, as the body grows, the strong connecting fibers in the dermis slowly stretch. However, with rapid growth, the fibers overstretch and break. Stretch marks are red or purple initially due to blood vessels showing through the tears in the dermis.

Stretch marks eventually fade to a silvery, white or glossy appearance due to the blood vessels contracting and the pale fat underneath the skin becoming visible instead.

Stretch marks have a more extreme appearance with an increase in cortisone, a hormone produced by the adrenal glands. Cortisone weakens elastic fibers in the skin.⁵⁷

Various risk factors have been reported to be associated with the development of stretch marks but the results are conflicting. Much remains to be understood about their epidemiology, diagnosis and treatment.^33,47

The pathogenesis of stretch marks is unknown but is likely to relate to changes in the fibroblast phenotype.³

A study that compared skin biopsies from normal subjects (NS), stretch-mark skin (SM) and normal-looking skin from patients with stretch marks (NL) found that:²

• NL skin contained less DNA, protein, and elastin than NS skin, with those deficiencies more profound in SM skin.
• NL and SM derived cells had slower than normal outgrowth of their fibroblasts, demonstrating low migration and proliferation rates, and producing less elastin, fibrillin 1, collagen 1, and fibronectin than NS-derived cells.

The skin structure of stretch marks is qualitatively and quantitatively different compared to healthy skin. Altered skin relief reflects structural modifications in the dermis.⁴⁸

A series of tests led to the discovery of a dormant phenotype in dermal fibroblasts from patients with stretch marks. These tests may help predict a predisposition to stretch marks and could open up a new approach for preventive treatments for people predisposed to stretch mark formation.²

The cause and associated factors for stretch mark occurrence could be linked to:^{14,17,21,30,33,39,53,54}

It has been proven that women with a higher BMI have an increased risk of stretch marks.

• Maternal age
• Hormone changes
• Genetic factors
• Inherited defects
• Pre-pregnancy BMI
• Maternal BMI at delivery
• Gestational age at delivery
• Birth weight of the baby
• Alcohol consumption
• Water intake
• Family history
• Physical stretching of the skin.

Women with higher body mass index (BMI) have more stretch marks. They are more frequently observed in younger women, with teenagers suffering the most severe stretch marks. These findings may be explained by the greater degrees of stretch applied to the skin in obese women with larger babies, and by changes in skin collagen and connective tissue that are age-related and affect its tendency to tear.^33,56

One study suggests that increased maternal age could be a protecting factor against stretch marks during pregnancy.²¹

It has been suggested that genetics may play a role in the development of stretch marks. Regardless of the etiology, all stretch marks display the same changes in the dermis, showing atrophy and loss of rete ridges (rete ridges are the downward projections of the epidermis that interlock with the papillary or superficial dermis). These findings are similar to those seen with scar formation.⁵⁵

Findings have also indicated that under certain conditions there is an increase in the hormonal receptor expression of estrogen, androgen and glucocorticoid, suggesting that regions that undergo greater mechanical stretching of the skin may express greater hormonal receptor activity.³⁹

Signs and symptoms

Before stretch marks begin to emerge, the skin can appear thin, pink and may feel irritated or itchy.

The marks initially develop as wrinkly, raised streaks that can be red, purple, pink, reddish-brown or dark brown, depending on skin color. The streaks eventually fade, flatten and change to a silvery color over time - sometimes years - and become less noticeable.

Tests and diagnosis

Stretch marks are easily diagnosed based on a skin examination and review of medical history. The doctor will usually ask questions based on signs and symptoms, medications being taken and any existing medical conditions.⁵⁸

Stretch marks are not harmful and do not cause medical problems.

Treatment and prevention

Creams, gels, lotions, laser and cosmetic surgery can be used as treatments for stretch marks, although there is little medical evidence to prove any of these are particularly effective or more consistent than the rest.²⁵Current treatments are limited in their ability to deliver long-lasting improvements for all skin types.³⁷

Often stretch marks fade over time and become unnoticeable. They are usually less noticeable 6-12 months after giving birth. Cosmetic camouflage (makeup) can be used to temporarily conceal marks.

The long-term future of treatment strategies is encouraging with advances in laser technologies.²⁶

Creams, oils, topical preparations

Several studies have found that when comparing topical preparations (something applied to the surface of the body) with active ingredients, with a placebo (preparations without active ingredients) or with no treatment for the prevention of stretch marks, there was no statistically significant difference in the development of stretch marks between the groups.

There is no high-quality evidence to support the use of topical preparations in the prevention of stretch marks during pregnancy.^9,10,43

Creams, oils and lotions do not seem to reduce the likelihood of stretch marks occurring.

Creams and oils do, however, help with skin dryness and may reduce itching.

Six studies involving 800 participants, including the use of preparations such as Alphastria, Trofolastin, Verum, olive oil and cocoa butter which all contain vitamin E (Alphastria and Verum also contain hyaluronic acid), there were no statistically significant average differences in the development of stretch marks.⁴³

One study evaluated the use of an anti-stretch mark cream containing hydroxyprolisilane-C, rosehip oil, Centella asiatica triterpenes and vitamin E, which proved to be effective in reducing the severity of the stretch marks during pregnancy, preventing the appearance of new stretch marks and halting progression of those already present. In women with no stretch marks, use of the anti-stretch mark cream was more effective than placebo in preventing new stretch marks.⁴⁵

Cocoa butter

In studies of 300 and 175 women, application of a lotion containing cocoa butter did not appear to reduce the likelihood of developing stretch marks during pregnancy.^27,52

Bitter almond oil

A study aiming to identify the effect of applying bitter almond oil with and without massage for preventing stretch marks during pregnancy found that a 15-minute massage applied with almond oil during pregnancy reduced the development of stretch marks, but using bitter almond oil had no effect on this in itself. It is recommended that pregnant women should be informed about the positive effects of massaging with applied almond oil early during their pregnancy.^40,51

Olive oil

Studies were performed in order to determine the effects of olive oil on stretch marks occurring within the second trimester of pregnancy, finding olive oil ineffective in reducing the occurrence or severity of stretch marks.^36,52

Olive oil has not been shown to significantly reduce stretch marks and is not recommended for stretch mark prevention.

Another study comparing 50 women applying topical olive oil twice a day with a control group applying none, showed that olive oil reduced the incidence of severe stretch marks and increased the incidence of mild stretch marks. 

Olive oil did not significantly reduce the incidence and the severity and could not be recommended for stretch mark prevention.⁴¹

Tretinoin cream (retinoic acid)

Tretinoin is extensively used in the treatment of acne as Retin-A and the treatment of stretch marks.^12,13

Studies indicate that the topical application of tretinoin significantly improves the clinical appearance of early stretch marks, although the process responsible for the clinical improvement is unknown.^15,20

In one study, tretinoin reduced the length of the stretch marks by 14% and the width by 8%. In another study, it decreased the length by 20%.

Note that products containing retinoic acid should not be used if pregnant or nursing.⁶¹

Tretinoin helps to rebuild collagen, which makes stretch marks look more like "normal" skin.⁵⁹

Silicone gel

A study of 20 volunteers who massaged silicone and placebo gels into separate sides of the abdomen daily for 6 weeks showed that the application of silicone gel increased collagen levels and reduced pigmentation compared with a placebo. These findings could provide preliminary evidence of the use of topical gels in the clinical management of stretch marks.⁴²

Microdermabrasion

Microdermabrasion is a popular technique used in the treatment of several skin problems, including acne, acne scarring, stretch marks, and photoaging. The procedure appears to result in an improvement in skin contour irregularities with significant improvement in early stretch marks.²²

This treatment involves a device that blows crystals onto the skin, "polishing" the skin's surface while a vacuum tube removes both the crystals and skin cells. The top layer of the skin is gently removed, stimulating growth of new elastic skin.⁵⁹

The treatment has a lower frequency of side effects and better adherence of the patients when compared with topical tretinoin.⁴⁶

Laser therapies

The use of lasers to diminish the appearance of stretch marks or in combination with other treatments can provide safe and effective reduction in the appearance of both red (early-onset) and white (late-stage) stretch marks. Many laser therapies require special measures for darker skin types, as pigmentary alterations are a major concern.^8,31

A doctor can give advice as to which form of laser treatment would be suitable. Laser therapies work by using wavelengths of light to stimulate growth of collagen, elastin or melanin production in the skin.⁵⁹

For early stretch marks, pulsed dye lasers have been shown effective, as has fractional laser treatment for older stretch marks.

Clinical improvements to stretch marks have been obtained with the following devices in studies by potentially stimulating new collagen and elastic fiber synthesis:

• 1,064-nm Nd:YAG laser²⁸
• 1540-nm fractional nonablative laser³⁷
• 1550-nm fractional nonablative laser³⁵
• Fractional CO2 laser^38,49
• Fractional photothermolysis²⁵
• Pulsed dye laser^6,16,31,50
• Copper bromide laser.⁵

Other

Other technologies that appear to have been promising alternative treatments for stretch marks during studies include:

Various medicinal herbs and combinations of botanicals have been claimed to treat stretch marks. There is no evidence that any of these work.

• Intense pulsed light (IPL)^7,44,50
• TriPollar radiofrequency device.²⁴

Alternative therapies such as plant extract gotu kola, aloe vera, combinations of botanicals, vitamins, tea tree oil, fruit acids, lemon juice, potato juice, egg whites and alfalfa are claimed to treat stretch marks. There is no evidence that these products work.⁶⁰

It has been demonstrated that ultrasound can diagnose stretch marks; PRIMOS devices can detect and measure stretch mark type and maturation.

A high-frequency ultrasound and 3D image device can be successfully employed in order to evaluate the effectiveness of a topical treatment.⁴¹

Ultimately, stretch marks cannot always be prevented, although these steps may help to reduce the risk:

• Maintain a healthy weight
• Avoid yo-yo dieting
• Eat a balanced diet rich in vitamins and minerals - particularly vitamins A and C and the minerals zinc and silicon for healthy skin
• Slow and gradual weight gain during pregnancy
• Drink plenty of water (6-8 glasses daily).

References:

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2.        Skin biopsy analysis reveals predisposition to stretch mark formation, Mitts TF, et al., Aesthetic surgery journal, November 2005.

3.        Contractile forces generated by striae distensae fibroblasts embedded in collagen lattices, Viennet C, Archives of dermatological research, July 2005.

4.        Histologic and ultrastructural analysis of ultraviolet B laser and light source treatment of leukoderma in striae distensae, Goldberg DJ, Dermatologic surgery, April 2005.

5.        Two-year follow-up results of copper bromide laser treatment of striae, Longo L, et al., Journal of clinical laser medicine and surgery, June 2003.

6.        Treatment of striae rubra and striae alba with the 585-nm pulsed-dye laser, Jiménez GP, et al., Dermatologic Surgery, April 2003.

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